Theo-Dur: Uses, Dosage & Side Effects
An extended-release theophylline bronchodilator for the management of asthma, chronic bronchitis, and emphysema-related bronchospasm
Theo-Dur (theophylline) is an extended-release oral bronchodilator belonging to the methylxanthine class of drugs. It works by relaxing the smooth muscles of the airways, widening the bronchial passages and making breathing easier. Theo-Dur is prescribed for the long-term management of asthma, chronic obstructive pulmonary disease (COPD) including chronic bronchitis, and bronchospasm associated with emphysema. The extended-release formulation allows for convenient twice-daily dosing. Theophylline has a narrow therapeutic index and requires careful dosing and regular blood level monitoring to ensure safety and effectiveness.
Quick Facts: Theo-Dur
Key Takeaways
- Theo-Dur (theophylline) is an extended-release bronchodilator that relaxes airway smooth muscle, relieving bronchospasm in asthma, COPD, and chronic bronchitis. It is taken twice daily for consistent symptom control.
- Theophylline has a narrow therapeutic index with a target serum concentration of 10–20 mcg/mL. Regular blood level monitoring is essential because even modest elevations above the therapeutic range can cause serious side effects including seizures and cardiac arrhythmias.
- Numerous drugs, foods, and lifestyle factors alter theophylline metabolism. Smoking accelerates clearance (requiring higher doses), while drugs like ciprofloxacin, erythromycin, and cimetidine inhibit metabolism and can cause dangerous blood level spikes.
- Extended-release tablets must never be crushed or chewed. Doing so destroys the controlled-release mechanism and can cause a dangerous rapid release of the full dose. Tablets may be split along the score line but halves must be swallowed whole.
- Theophylline is not recommended as a first-line treatment for asthma in children or adults. Current guidelines (GINA 2024, GOLD 2024) position it as add-on therapy when inhaled bronchodilators and corticosteroids are insufficient.
What Is Theo-Dur and What Is It Used For?
Theo-Dur contains the active substance theophylline, one of the oldest and most extensively studied bronchodilators in clinical medicine. Theophylline belongs to the methylxanthine family of compounds, which are naturally occurring substances found in tea leaves, coffee beans, and cocoa. As a pharmaceutical agent, theophylline has been used for the treatment of respiratory diseases for over a century, and it remains an important therapeutic option worldwide, particularly in settings where access to newer inhaled therapies is limited.
The primary pharmacological action of theophylline is relaxation of bronchial smooth muscle. When the muscles surrounding the airways contract abnormally — as occurs in asthma and COPD — the airways become narrowed, making breathing difficult. Theophylline counteracts this bronchospasm through multiple mechanisms. It inhibits phosphodiesterase (PDE) enzymes, particularly PDE III and PDE IV, which leads to increased intracellular concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). These second messengers promote smooth muscle relaxation and bronchodilation. Theophylline also acts as a non-selective antagonist at adenosine A1 and A2 receptors, further contributing to bronchodilation and potentially to anti-inflammatory effects.
Beyond its bronchodilator effects, research over recent decades has revealed that theophylline possesses important anti-inflammatory and immunomodulatory properties at therapeutic concentrations. At serum levels of 5–10 mcg/mL, theophylline can suppress airway inflammation by inhibiting the release of inflammatory mediators from mast cells and reducing eosinophilic infiltration of the airways. It has also been shown to enhance the activity of histone deacetylase-2 (HDAC2), an enzyme that is important for the anti-inflammatory actions of corticosteroids. This property has led to interest in using low-dose theophylline as a corticosteroid-sparing agent, particularly in patients with COPD who show reduced corticosteroid responsiveness.
Theo-Dur is specifically formulated as an extended-release (also called sustained-release or modified-release) tablet. Unlike conventional immediate-release theophylline formulations that produce rapid peaks and troughs in blood levels, Theo-Dur slowly releases theophylline over an extended period. This controlled-release mechanism provides more stable blood levels throughout the day, reduces the frequency of side effects associated with peak concentrations, and allows for convenient twice-daily dosing rather than three or four times daily.
Theo-Dur is prescribed for the following conditions:
- Asthma: As maintenance therapy for the prevention and treatment of bronchospasm in patients with asthma. Current international guidelines (GINA 2024) position theophylline as an add-on therapy at Steps 3–5, used when patients remain symptomatic despite inhaled corticosteroids and long-acting beta-agonists. It is not recommended as a first-line controller medication.
- Chronic obstructive pulmonary disease (COPD): For the long-term management of airflow limitation and symptoms in COPD, including chronic bronchitis and emphysema. The GOLD 2024 guidelines consider theophylline as an option when inhaled bronchodilators are unavailable or unaffordable, noting its modest bronchodilator effect and potential anti-inflammatory benefits at lower doses.
- Chronic bronchitis with bronchospasm: To relieve bronchospasm in patients with chronic inflammation of the bronchial tubes, where mucus production and airway narrowing cause persistent cough, mucus production, and difficulty breathing.
- Emphysema-related bronchospasm: To ease breathing difficulties in patients with emphysema, a condition characterized by damage to the alveoli (air sacs) in the lungs, leading to reduced gas exchange and progressive shortness of breath.
Theophylline is included on the World Health Organization (WHO) Model List of Essential Medicines, recognizing its importance as a bronchodilator worldwide. While newer inhaled medications have largely replaced theophylline as first-line therapy in high-income countries, it remains widely used globally due to its oral administration, low cost, and demonstrated efficacy across decades of clinical use.
What Should You Know Before Taking Theo-Dur?
Contraindications
Theophylline should not be used in certain circumstances where the risks clearly outweigh the potential benefits. Understanding these contraindications is essential before initiating treatment.
- Hypersensitivity: Do not take Theo-Dur if you are allergic to theophylline or any of the other ingredients in the product, including lactose, sugar spheres, hypromellose, magnesium stearate, glycerol monostearate, white wax, cetyl alcohol, myristyl alcohol, cellulose acetate phthalate, and diethyl phthalate.
- Uncontrolled seizure disorder: Theophylline lowers the seizure threshold and should be used with extreme caution, if at all, in patients with active, uncontrolled epilepsy. Any patient with a history of seizures requires careful risk-benefit assessment and close monitoring.
- Active peptic ulcer disease: Theophylline stimulates gastric acid secretion and may worsen peptic ulcer disease. Use with caution in patients with active gastrointestinal bleeding.
Warnings and Precautions
Theophylline has a very narrow margin between therapeutic and toxic serum concentrations. The therapeutic range is 10–20 mcg/mL (55–110 micromol/L). Serum concentrations above 20 mcg/mL significantly increase the risk of severe adverse effects including cardiac arrhythmias, seizures (which may occur without prior warning signs), and potentially fatal outcomes. Regular serum level monitoring is essential, particularly when initiating therapy, adjusting doses, or adding interacting medications.
Talk to your doctor before taking Theo-Dur if you have any of the following conditions, as dose adjustments or additional monitoring may be necessary:
- Hepatic impairment: Theophylline is extensively metabolized in the liver by cytochrome P450 enzymes (predominantly CYP1A2). Patients with liver disease have significantly reduced clearance and may require substantially lower doses. Liver disease of any cause — including cirrhosis, acute hepatitis, and cholestasis — can result in dangerously elevated theophylline blood levels at standard doses.
- Cardiovascular disease: Theophylline can cause tachycardia (increased heart rate) and cardiac arrhythmias. Patients with pre-existing cardiovascular conditions, including coronary artery disease, congestive heart failure, and arrhythmias, require lower initial doses and more frequent monitoring. Heart failure itself reduces theophylline clearance, further increasing the risk of toxicity.
- Epilepsy or history of seizures: Theophylline lowers the seizure threshold. Patients with epilepsy or a history of seizures are at increased risk of theophylline-induced convulsions, which can occur at serum levels within or slightly above the therapeutic range.
- Hyperthyroidism: Thyroid dysfunction can affect theophylline metabolism. Hyperthyroid patients may have increased clearance, while hypothyroid patients may have decreased clearance.
- Fever and acute illness: Fever, particularly sustained fever above 38°C (100.4°F) for 24 hours or more, can decrease theophylline clearance by up to 50%. Viral respiratory infections are particularly associated with reduced clearance. Contact your doctor if you develop fever or an acute illness during theophylline treatment, as dose reduction may be required.
Tobacco smoke and marijuana smoke induce the CYP1A2 enzyme, which accelerates theophylline metabolism. Smokers typically require 1.5–2 times the theophylline dose of non-smokers to achieve equivalent serum levels. If you stop smoking while taking Theo-Dur, you must inform your doctor immediately. Following smoking cessation, CYP1A2 induction reverses over approximately 1–2 weeks, causing theophylline blood levels to rise and potentially reach toxic concentrations. Your dose will need to be reduced, typically by 25–50%.
Pregnancy and Breastfeeding
If you are pregnant, breastfeeding, think you may be pregnant, or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
Pregnancy: Theophylline crosses the placenta, and the fetus is exposed to maternal serum concentrations. Current evidence does not indicate a significant increase in birth defects or adverse pregnancy outcomes with theophylline use at therapeutic doses. However, theophylline pharmacokinetics change during pregnancy: clearance increases during the third trimester, potentially requiring dose adjustments. Neonatal toxicity, including irritability and tachycardia, has been reported when maternal serum levels are elevated. Theophylline should be used during pregnancy only when the clinical benefit justifies the potential risk, and serum levels should be monitored more frequently.
Breastfeeding: Theophylline passes into breast milk at concentrations approximately 70% of the maternal serum level. While this exposure is generally considered unlikely to cause clinically significant effects in the nursing infant at therapeutic maternal doses, irritability and poor feeding have been reported in some breastfed infants. If you are breastfeeding, discuss the benefits and risks with your doctor, particularly if treatment will be ongoing.
Excipient Warnings
Theo-Dur extended-release tablets contain lactose (62.4 mg per 200 mg tablet, 93.8 mg per 300 mg tablet) and sucrose (as sugar spheres). If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine. Patients with rare hereditary conditions of galactose intolerance, total lactase deficiency, glucose-galactose malabsorption, or fructose intolerance should not take this medicine.
How Does Theo-Dur Interact with Other Drugs?
Theophylline has one of the most extensive drug interaction profiles of any commonly used medication. Because it is metabolized primarily by the hepatic cytochrome P450 enzyme CYP1A2 (with contributions from CYP3A4 and CYP2E1), any drug that inhibits or induces these enzymes can significantly alter theophylline serum concentrations. Given the narrow therapeutic index, even modest changes in blood levels can have clinically important consequences — either loss of bronchodilator effect or development of toxicity.
The following table summarizes the most clinically significant drug interactions with theophylline. This list is not exhaustive; always inform your doctor and pharmacist about all medications, supplements, and herbal products you are taking.
Major Interactions (Require Dose Adjustment or Avoidance)
| Drug | Effect on Theophylline | Clinical Significance |
|---|---|---|
| Ciprofloxacin | Increases levels by 20–40% | Strong CYP1A2 inhibitor. Dose reduction required. Risk of toxicity. |
| Erythromycin | Increases levels by 25–35% | CYP3A4 inhibitor. Monitor levels and adjust dose. |
| Cimetidine | Increases levels by 20–40% | CYP1A2 inhibitor. Consider ranitidine as alternative (lesser interaction). |
| Fluvoxamine | Increases levels by 200–300% | Very potent CYP1A2 inhibitor. Combination generally contraindicated. |
| Rifampicin | Decreases levels by 25–50% | Potent CYP inducer. Significant dose increase usually needed. |
| Phenytoin | Decreases levels; mutual interaction | Both drugs affect each other's metabolism. Monitor levels of both. |
| Phenobarbital | Decreases levels by 25–30% | Enzyme inducer. Dose increase may be needed. |
| Norfloxacin | Increases levels moderately | CYP1A2 inhibitor, though less potent than ciprofloxacin. |
Other Important Interactions
| Drug | Interaction | Notes |
|---|---|---|
| Adenosine | Theophylline blocks adenosine effects | Higher adenosine doses needed for cardiac diagnostic tests. |
| Propranolol | Mutual antagonism + reduced clearance | Beta-blockers can worsen bronchospasm; propranolol also inhibits theophylline metabolism. |
| Verapamil | Increases theophylline levels | Calcium channel blocker; monitor serum levels. |
| Lithium | Theophylline increases lithium excretion | May reduce lithium efficacy. Monitor lithium levels. |
| Diazepam (Benzodiazepines) | Theophylline may reduce sedative effects | CNS stimulation by theophylline can partially counteract benzodiazepine sedation. |
| Allopurinol | May increase theophylline levels at high doses | Clinically significant mainly at allopurinol doses ≥600 mg/day. |
| Halothane / Ketamine | Increased risk of cardiac arrhythmias | Inform anesthesiologist if you take theophylline before any surgery. |
| St. John’s Wort | May decrease theophylline levels | Herbal CYP inducer. Avoid concurrent use. |
| Methotrexate | Theophylline may reduce methotrexate clearance | Monitor for methotrexate toxicity if used together. |
| Aciclovir | May increase theophylline levels | Monitor theophylline levels during concurrent antiviral therapy. |
High-protein, low-carbohydrate diets can increase theophylline clearance by up to 25%, while high-carbohydrate, low-protein diets can decrease clearance. Charcoal-grilled foods contain polycyclic aromatic hydrocarbons that induce CYP1A2 and can reduce theophylline levels. Large amounts of caffeine-containing beverages (coffee, tea, cola) should be consumed with caution, as caffeine is a methylxanthine closely related to theophylline and can potentiate adverse effects such as nervousness, insomnia, and tachycardia.
What Is the Correct Dosage of Theo-Dur?
Always take Theo-Dur exactly as your doctor or pharmacist has told you. The dose is individualized based on body weight, clinical response, and serum theophylline concentration. Dosing must be conservative, particularly in elderly patients and those with liver disease or heart failure, because of the narrow therapeutic index. Your doctor will adjust the dose based on periodic blood tests measuring theophylline levels.
Adults
Standard Adult Dosage
Starting dose: 200–300 mg twice daily (every 12 hours).
Titration: The dose may be increased in increments of 100–200 mg/day at intervals of at least 3 days, guided by serum theophylline levels and clinical response.
Maximum dose: Generally not exceeding 800–900 mg/day, though individual requirements vary. The dose should always be guided by serum level monitoring.
Target serum concentration: 10–20 mcg/mL (55–110 micromol/L). Some guidelines suggest targeting the lower end of this range (10–15 mcg/mL) to minimize side effects.
Patients with cardiovascular disease or hepatic impairment may require a significantly lower starting dose, often 50% of the standard dose, with cautious upward titration based on serum level monitoring. Heart failure reduces theophylline clearance by up to 50%, and liver disease can reduce clearance even further.
Children
Pediatric Dosage
Children 6–12 years: Dosage is based on body weight, typically 12–14 mg/kg/day divided into two doses (every 12 hours), not exceeding 600 mg/day. Serum level monitoring is essential.
Children over 12 years: May use adult dosing guidelines with careful monitoring.
Children under 6 years: Theo-Dur extended-release tablets should not be used in children under 6 years of age. Other theophylline formulations (such as oral liquid) that allow more precise weight-based dosing are more appropriate for this age group.
Theophylline is not recommended as first-line treatment for asthma in children. The Global Initiative for Asthma (GINA) and other international guidelines recommend inhaled corticosteroids as the preferred controller therapy, with theophylline considered only as an add-on option when preferred treatments are insufficient or unavailable. Children metabolize theophylline more rapidly than adults and generally require higher weight-adjusted doses, but they are also more susceptible to toxicity.
Elderly Patients
Elderly Dosage Considerations
Elderly patients (over 65 years) typically have reduced theophylline clearance due to age-related decreases in hepatic function. Starting doses should be conservative, generally beginning at the lower end of the dosing range (200 mg twice daily or less). Dose adjustments should be made slowly, with frequent serum level monitoring. Elderly patients are also more susceptible to the cardiovascular side effects of theophylline, including tachycardia and arrhythmias.
Missed Dose
If you forget to take a dose, take it as soon as you remember. However, if it is nearly time for your next scheduled dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a forgotten one. Taking two doses close together increases the risk of side effects, including nausea, rapid heartbeat, and tremor.
Overdose
If you have taken more Theo-Dur than prescribed, or if a child has accidentally ingested the medication, contact your local emergency services or poison control center immediately. Theophylline overdose is a medical emergency. The most common and serious symptoms of overdose include rapid and irregular heartbeat (potentially life-threatening cardiac arrhythmias), seizures (which may occur without warning and can be refractory to standard treatment), persistent vomiting, agitation, and metabolic disturbances. Activated charcoal and, in severe cases, hemoperfusion or hemodialysis may be required. Extended-release formulations pose a particular danger in overdose because drug continues to be absorbed for many hours after ingestion.
Theo-Dur extended-release tablets are scored and may be split in half along the score line if needed. However, halved or whole tablets must be swallowed without crushing or chewing, with at least half a glass of water. Crushing or chewing the tablet destroys the extended-release mechanism and can cause a dangerous rapid release of the full dose (“dose dumping”), potentially leading to toxic serum concentrations.
What Are the Side Effects of Theo-Dur?
Like all medicines, Theo-Dur can cause side effects, although not everybody gets them. The side effects of theophylline are closely related to serum concentration. At therapeutic levels (10–20 mcg/mL), side effects are generally mild and often transient. As concentrations rise above 20 mcg/mL, the risk and severity of adverse effects increase markedly. This dose-dependent toxicity profile underscores the importance of regular serum level monitoring throughout treatment.
Many patients experience some gastrointestinal or central nervous system side effects when starting theophylline, particularly at higher initial doses. These effects frequently diminish after a few days of treatment as the body adjusts, or they may resolve with a modest dose reduction. However, certain serious adverse effects — notably seizures and cardiac arrhythmias — can occur suddenly, sometimes at serum levels only slightly above the therapeutic range, and require immediate medical attention.
Common
May affect more than 1 in 100 patients
- Nausea and vomiting
- Loss of appetite
- Tremor (shakiness)
- Sleep disturbances (insomnia)
- Irritability and nervousness
- Headache
Uncommon
May affect up to 1 in 100 patients
- Urticaria (hives)
- Skin rash
- Abdominal pain
- Gastroesophageal reflux
- Diarrhea
- Restlessness and agitation
Rare
May affect up to 1 in 1,000 patients
- Muscle cramps
- Rapid and irregular heartbeat (tachyarrhythmia)
- Seizures (convulsions)
- Hypotension (low blood pressure)
- Increased urine output (diuresis)
The gastrointestinal side effects of theophylline — nausea, vomiting, and loss of appetite — are among the most common reasons patients discontinue treatment. These effects are typically dose-related and often improve when the dose is reduced or when the medication is taken with food. However, persistent or severe vomiting can also be a sign of theophylline toxicity and should prompt immediate serum level measurement.
Central nervous system effects such as tremor, insomnia, nervousness, and headache reflect theophylline’s stimulant properties as a methylxanthine. These symptoms are similar to caffeine excess and are dose-dependent. In severe toxicity, CNS stimulation can progress to agitation, confusion, and generalized tonic-clonic seizures. Theophylline-induced seizures are particularly dangerous because they tend to be prolonged, difficult to treat with conventional anticonvulsants, and are associated with significant morbidity and mortality.
Cardiac side effects are primarily seen at elevated serum concentrations but can occasionally occur within the therapeutic range, particularly in patients with pre-existing cardiac disease. Sinus tachycardia is the most common cardiac manifestation, but more serious arrhythmias — including atrial fibrillation, multifocal atrial tachycardia, and ventricular arrhythmias — have been reported with theophylline toxicity.
Contact your doctor or seek emergency medical care immediately if you experience any of the following: rapid or irregular heartbeat (palpitations), seizures or convulsions, persistent vomiting, severe restlessness or agitation, confusion, or chest pain. These may be signs of theophylline toxicity, which requires urgent medical evaluation including serum theophylline level measurement.
How Should You Store Theo-Dur?
Proper storage of Theo-Dur is important to maintain the medication’s quality, safety, and effectiveness throughout its shelf life. The extended-release formulation is particularly sensitive to environmental conditions, as degradation of the controlled-release coating could alter the drug release profile and potentially lead to unpredictable absorption.
- Temperature: Store at or below 30°C (86°F). Do not expose to excessive heat or freezing temperatures. Avoid storing in bathrooms or near heat sources.
- Children: Keep this medicine out of the sight and reach of children. The plastic containers come with child-resistant screw caps, but these are not child-proof. Always store medications in a secure location.
- Expiration date: Do not use Theo-Dur after the expiration date stated on the label. The expiration date refers to the last day of that month.
- Disposal: Do not throw away medications in wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help to protect the environment.
Theo-Dur is supplied in plastic containers with child-resistant screw caps containing 100 extended-release tablets. The 200 mg tablets are white, oval-shaped, with a score line on one side and “THEO-DUR 200” engraved on the other. The 300 mg tablets are white, oblong (rod-shaped), with a score line on one side and “THEO-DUR 300” engraved on the other.
What Does Theo-Dur Contain?
Understanding what Theo-Dur contains is important for identifying potential allergens and excipients that might affect tolerability. The active substance provides the therapeutic effect, while the inactive ingredients (excipients) are essential for the extended-release mechanism that allows twice-daily dosing.
| Component | 200 mg Tablet | 300 mg Tablet |
|---|---|---|
| Theophylline (active) | 200 mg | 300 mg |
| Lactose | 62.4 mg | 93.8 mg |
| Sugar spheres (sucrose) | 70 mg | 105 mg |
| Hypromellose | Controlled-release coating | |
| Magnesium stearate | Lubricant | |
| Glycerol monostearate | Emulsifier | |
| White wax, cetyl & myristyl alcohol | Matrix components | |
| Cellulose acetate phthalate | Enteric coating | |
| Diethyl phthalate | Plasticizer | |
The excipients in Theo-Dur tablets serve critical functions in achieving the extended-release drug delivery. Hypromellose, waxes, and alcohols form a matrix that controls the rate of theophylline release from the tablet, ensuring a slow and steady absorption over approximately 12 hours. Cellulose acetate phthalate provides an enteric coating component, and diethyl phthalate acts as a plasticizer to maintain coating flexibility. These inactive ingredients are present in small quantities and are generally well tolerated, though patients with known intolerance to lactose or sucrose should be aware of their presence in the formulation.
Frequently Asked Questions About Theo-Dur
Theo-Dur is an extended-release (sustained-release) formulation of theophylline, while regular theophylline tablets are immediate-release. The key differences are: Theo-Dur releases theophylline slowly over approximately 12 hours, allowing twice-daily dosing, while immediate-release tablets must be taken 3–4 times daily. Extended-release formulations also produce more stable blood levels with fewer peaks and troughs, which generally means fewer side effects. However, Theo-Dur tablets must not be crushed or chewed, as this would destroy the controlled-release mechanism and could cause dangerous dose dumping.
Theophylline serum levels should be checked when starting treatment (typically after achieving steady state, about 3 days of consistent dosing), after any dose change, when adding or removing interacting medications, when clinical status changes (e.g., new illness, hospitalization, smoking cessation), and at least every 6–12 months during stable long-term treatment. Blood samples for trough levels should ideally be drawn just before the next scheduled dose. The target therapeutic range is 10–20 mcg/mL, with many clinicians aiming for 10–15 mcg/mL to minimize toxicity risk.
Theo-Dur extended-release tablets can be taken with or without food. Taking them with food may reduce gastrointestinal side effects such as nausea. However, dietary changes can affect theophylline absorption and metabolism. High-fat meals may alter the rate of drug release from some extended-release formulations. It is generally recommended to take Theo-Dur consistently with respect to meals — either always with food or always on an empty stomach — to maintain consistent drug absorption. Large amounts of caffeine-containing beverages should be limited, as caffeine can add to theophylline’s stimulant effects.
Yes, theophylline is still used for asthma, though its role has changed considerably over the decades. Current guidelines (GINA 2024) position it as add-on therapy rather than a first-line treatment. Inhaled corticosteroids and long-acting beta-agonists are preferred because they are more effective and better tolerated. Theophylline may be considered at GINA Steps 3–5 when patients remain inadequately controlled on preferred therapies, when cost or availability limits access to inhaled medications, or as a corticosteroid-sparing agent. Low-dose theophylline (targeting serum levels of 5–10 mcg/mL) has shown anti-inflammatory properties that may complement inhaled corticosteroid therapy.
Both caffeine and theophylline belong to the methylxanthine family and share similar pharmacological effects. Consuming large amounts of coffee, tea, cola, energy drinks, or chocolate while taking Theo-Dur can intensify side effects such as nervousness, anxiety, tremor, insomnia, heart palpitations, and gastrointestinal discomfort. While moderate caffeine intake is generally tolerable for most patients on theophylline, excessive caffeine consumption should be avoided. Your doctor may advise you on a safe caffeine limit based on your theophylline dose and individual sensitivity.
Theo-Dur is not expected to significantly impair your ability to drive or operate machinery at normal therapeutic doses. However, some patients may experience side effects such as dizziness, headache, tremor, nervousness, or insomnia that could potentially affect concentration and reaction time. If you experience any such effects, use caution when driving or operating heavy machinery until you know how the medication affects you. If these effects are significant, contact your doctor about possible dose adjustment.
References
- Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention, 2024 Update. Available at: ginasthma.org
- Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease, 2024 Report. Available at: goldcopd.org
- British National Formulary (BNF). Theophylline Monograph. National Institute for Health and Care Excellence (NICE), 2025.
- World Health Organization (WHO). Model List of Essential Medicines, 23rd List, 2023. Geneva: WHO.
- Barnes PJ. Theophylline. Am J Respir Crit Care Med. 2013;188(8):901-906. doi:10.1164/rccm.201302-0388PP
- Jilani TN, Preuss CV, Sharma S. Theophylline. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.
- European Medicines Agency (EMA). Theophylline Product Information. Summary of Product Characteristics.
- U.S. Food and Drug Administration (FDA). Theophylline Prescribing Information.
- Rabe KF, et al. Therapeutic potential of theophylline in chronic obstructive pulmonary disease. Expert Rev Respir Med. 2011;5(2):159-167.
- Cosio BG, et al. Theophylline restores histone deacetylase activity and steroid responses in COPD macrophages. J Exp Med. 2004;200(5):689-695.
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