Serevent Evohaler (Salmeterol)
Long-acting bronchodilator inhaler for asthma and COPD prevention
Serevent Evohaler contains salmeterol, a long-acting beta-2 agonist (LABA) that relaxes the airways in the lungs and makes breathing easier for up to 12 hours. It is prescribed to prevent breathing difficulties in asthma and chronic obstructive pulmonary disease (COPD). Serevent is a preventive inhaler — it is not a rescue inhaler for sudden attacks.
Quick Facts
Key Takeaways
- Serevent Evohaler is a preventive inhaler taken twice daily — it is not a rescue inhaler for acute asthma attacks.
- For asthma, it must always be used together with an inhaled corticosteroid (ICS). Never use salmeterol alone for asthma.
- The bronchodilator effect begins within 10–20 minutes and lasts at least 12 hours, making twice-daily dosing effective around the clock.
- Common side effects include tremor, headache, and muscle cramps — these typically decrease with continued use.
- Avoid strong CYP3A4 inhibitors (ketoconazole, ritonavir) and beta-blockers, which can interact significantly with salmeterol.
What Is Serevent Evohaler and What Is It Used For?
Serevent Evohaler belongs to a class of medicines known as long-acting beta-2 adrenergic agonists (LABAs). The active ingredient, salmeterol, selectively stimulates beta-2 receptors found on the smooth muscle of the airways in the lungs. When these receptors are activated, the airway muscles relax, the bronchial tubes widen, and airflow improves significantly. Unlike short-acting bronchodilators such as salbutamol, salmeterol has a unique molecular structure with a long lipophilic side chain that anchors it near the beta-2 receptor, allowing it to provide sustained bronchodilation for 12 hours or more after each dose.
In asthma management, Serevent Evohaler is prescribed as an add-on therapy for patients whose symptoms are not adequately controlled by inhaled corticosteroids (ICS) alone. According to the Global Initiative for Asthma (GINA) 2024 guidelines, the addition of a LABA to an ICS is a cornerstone of Step 3–5 asthma treatment. By taking Serevent regularly, patients experience fewer asthma episodes, reduced nighttime symptoms, and improved lung function. It is particularly beneficial for exercise-induced bronchoconstriction and nocturnal asthma, where the long duration of action provides sustained protection.
For chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema, Serevent Evohaler provides regular bronchodilation that helps patients breathe more easily throughout the day. The European Respiratory Society (ERS) and the American Thoracic Society (ATS) recommend long-acting bronchodilators as maintenance therapy for patients with persistent COPD symptoms. In COPD, salmeterol has been shown to reduce exacerbations, improve quality of life scores, and enhance exercise tolerance.
Serevent Evohaler is a preventive medicine. It does not provide immediate relief during an acute asthma attack or sudden worsening of COPD symptoms. Always carry a separate short-acting rescue inhaler (such as salbutamol) for sudden breathing difficulties. If you find yourself needing your rescue inhaler more frequently, contact your doctor as your condition may be worsening.
Serevent Evohaler is a pressurised metered-dose inhaler (pMDI) that delivers the medicine as a fine mist directly into the lungs. Each canister contains 120 metered doses of salmeterol 25 micrograms per actuation. The medicine is inhaled through the mouth, reaching the target tissue in the airways with minimal systemic absorption, which reduces the potential for whole-body side effects compared to oral medications.
The product is approved and marketed in numerous countries across the European Economic Area, the United Kingdom, and internationally under the brand names Serevent and Serevent Evohaler. It has a well-established safety profile supported by decades of clinical use and extensive post-marketing surveillance data.
What Should You Know Before Taking Serevent Evohaler?
Contraindications
Serevent Evohaler should not be used if you have a known hypersensitivity (allergy) to salmeterol or to the excipient norfluran (HFA 134a), which is the propellant used in the inhaler. Allergic reactions to salmeterol are extremely rare but can include skin rash, facial swelling, and in very rare cases, anaphylaxis. If you have experienced any allergic reaction to salmeterol or a similar long-acting bronchodilator in the past, do not use this medicine and inform your healthcare provider.
Salmeterol should never be used as monotherapy for asthma without concurrent inhaled corticosteroid treatment. Large clinical trials, including the Salmeterol Multicenter Asthma Research Trial (SMART), identified a potential increased risk of serious asthma-related events when LABAs are used without an ICS. This led to regulatory updates worldwide requiring that LABAs for asthma always be prescribed alongside an ICS. If you have asthma, your doctor will prescribe an inhaled corticosteroid to take together with Serevent Evohaler, or may switch you to a combination inhaler containing both medicines.
Warnings and Precautions
If your asthma or breathing worsens after starting Serevent Evohaler, contact your doctor immediately. Signs of deterioration include increasing wheeze, chest tightness, and needing your rescue inhaler more often. Do not simply increase the dose of Serevent — your overall treatment plan may need adjustment. When your asthma is well controlled, your doctor may gradually reduce the Serevent dose.
Your doctor should monitor you more closely if you have any of the following conditions:
- Hyperthyroidism (overactive thyroid gland) — salmeterol may increase heart rate and blood pressure
- Diabetes mellitus — salmeterol can raise blood glucose levels; more frequent monitoring may be needed
- Cardiovascular disease — including coronary artery disease, heart rhythm disorders, or hypertension
- Hypokalaemia (low potassium) — beta-2 agonists can further reduce serum potassium levels, particularly when combined with certain other medications
Do not stop taking your inhaled corticosteroid or corticosteroid tablets when you start using Serevent Evohaler. Even if you feel much better, continue all your prescribed asthma medications at the same doses unless your doctor specifically advises otherwise. Abrupt discontinuation of corticosteroid therapy can trigger a severe asthma exacerbation or adrenal insufficiency.
Pregnancy and Breastfeeding
If you are pregnant, planning a pregnancy, or breastfeeding, consult your doctor before using Serevent Evohaler. There is limited clinical data on the use of salmeterol during pregnancy. Animal studies have shown some reproductive effects at very high doses, but the relevance to human therapeutic doses is uncertain. Your doctor will carefully weigh the benefits of controlling your asthma or COPD against any potential risks to the baby.
Uncontrolled asthma during pregnancy poses significant risks, including pre-eclampsia, premature birth, low birth weight, and maternal hypoxia. International guidelines, including those from GINA and the British Thoracic Society (BTS), emphasise that it is safer to treat asthma during pregnancy than to leave it uncontrolled. The decision to continue, adjust, or change your inhaler therapy should always be made in consultation with your healthcare provider.
It is not known whether salmeterol passes into breast milk in clinically significant amounts. As with other medicines, your doctor will assess the benefit of breastfeeding alongside the benefit of treatment for you before making a recommendation.
Driving and Operating Machinery
Serevent Evohaler is unlikely to affect your ability to drive or operate machinery. Side effects such as tremor or dizziness are uncommon and generally mild. However, you should be aware of how this medicine affects you personally before driving. If you experience any symptoms that could impair your concentration or coordination, avoid driving until the effects subside and discuss them with your doctor.
How Does Serevent Evohaler Interact with Other Drugs?
Salmeterol is primarily metabolised by the cytochrome P450 enzyme CYP3A4 in the liver. Medicines that strongly inhibit this enzyme can significantly increase the systemic concentration of salmeterol, leading to a higher risk of adverse effects including QT prolongation and cardiac arrhythmias. Always inform your doctor about all medications you are taking, including prescription drugs, over-the-counter medicines, and herbal supplements.
Major Interactions
| Drug / Drug Class | Interaction Type | Clinical Significance |
|---|---|---|
| Ketoconazole | Strong CYP3A4 inhibitor | Significantly increases salmeterol exposure; avoid concomitant use. Risk of QT prolongation and cardiac arrhythmia. |
| Itraconazole | Strong CYP3A4 inhibitor | Similar to ketoconazole; increased salmeterol levels and cardiovascular risk. Avoid combination. |
| Ritonavir (and other HIV protease inhibitors) | Strong CYP3A4 inhibitor | Marked increase in salmeterol exposure. Risk of prolonged QTc, palpitations, and sinus tachycardia. Combination not recommended. |
| Beta-blockers (e.g. atenolol, propranolol, sotalol) | Pharmacological antagonist | May diminish or block bronchodilator effect of salmeterol. Avoid non-selective beta-blockers. Cardioselective agents used with caution. |
The interaction between salmeterol and strong CYP3A4 inhibitors is clinically important. A pharmacokinetic study showed that co-administration of ketoconazole (400 mg once daily) with salmeterol (50 mcg inhaled twice daily) resulted in a 15-fold increase in salmeterol plasma exposure, with significant increases in heart rate and QTc prolongation. This combination should be avoided. If antifungal treatment is necessary, consider alternatives that do not strongly inhibit CYP3A4, such as fluconazole.
Other Interactions to Be Aware Of
| Drug / Drug Class | Interaction Type | Clinical Significance |
|---|---|---|
| Diuretics (e.g. furosemide, hydrochlorothiazide) | Additive hypokalaemia | Both drugs can lower potassium. Monitor serum potassium levels, especially in patients with cardiac disease. |
| Theophylline | Additive hypokalaemia | Xanthine derivatives may potentiate potassium-lowering effect. Blood tests may be required to monitor potassium levels. |
| Systemic corticosteroids | Additive hypokalaemia | High-dose or prolonged systemic corticosteroid use alongside beta-2 agonists may further reduce potassium. Monitor levels. |
| Other LABAs (e.g. formoterol) | Additive beta-2 stimulation | Do not use two LABAs concurrently. Increases risk of cardiovascular side effects without additional clinical benefit. |
Symptoms of hypokalaemia (low potassium) can include irregular heartbeat, muscle weakness, and cramps. If you are taking any of the medicines listed above alongside Serevent Evohaler, your doctor may request periodic blood tests to monitor your potassium levels. This is particularly important for patients with underlying cardiac conditions, where electrolyte imbalances can increase the risk of arrhythmias.
What Is the Correct Dosage of Serevent Evohaler?
Always use Serevent Evohaler exactly as prescribed by your doctor or pharmacist. The medicine should be used regularly every day, even when you feel well, until your doctor advises you to stop. You will typically notice the benefit from the first day of use. The inhaler should be used at approximately the same times each day — usually morning and evening — to maintain consistent bronchodilation over 24 hours.
Adults and Adolescents (12 years and older)
Asthma
Standard dose: 2 inhalations (2 × 25 mcg = 50 mcg) twice daily
Severe asthma: Up to 4 inhalations (4 × 25 mcg = 100 mcg) twice daily, only under medical supervision
COPD (Chronic Obstructive Pulmonary Disease)
Standard dose: 2 inhalations (2 × 25 mcg = 50 mcg) twice daily
The dose for COPD does not usually exceed 50 mcg twice daily.
Children (4 to 12 years)
Paediatric Asthma
Standard dose: 2 inhalations (2 × 25 mcg = 50 mcg) twice daily
Serevent Evohaler is not recommended for children under 4 years of age due to insufficient data on safety and efficacy in this age group.
If you or your child find it difficult to coordinate pressing the canister and breathing in at the same time, a spacer device (also called a valved holding chamber) can be attached to the inhaler. The spacer holds the aerosolised medicine in a chamber, allowing you to breathe it in at your own pace. Ask your doctor, nurse, or pharmacist for advice on suitable spacer devices.
Elderly Patients
No dose adjustment is required for elderly patients. The standard adult dosing applies. However, elderly patients may be more susceptible to cardiovascular side effects such as palpitations and tremor. If you experience these symptoms, inform your doctor, who may wish to monitor you more closely or adjust your treatment regimen. Elderly patients with COPD often have multiple comorbidities and take several medications, so the potential for drug interactions should be carefully reviewed.
How to Use the Inhaler
Proper inhaler technique is essential for the medicine to reach your lungs effectively. Studies show that a significant proportion of patients use their inhalers incorrectly, reducing the amount of medicine delivered to the airways. Your doctor, nurse, or pharmacist should demonstrate the correct technique and periodically check that you are using the inhaler properly.
- Remove the mouthpiece cap by gently squeezing both sides. Check the mouthpiece inside and outside for cleanliness and any foreign objects.
- Shake the inhaler well 4–5 times to mix the contents. If using for the first time or if it has not been used for a week or more, release two test sprays into the air away from your face.
- Breathe out gently and as fully as comfortable while holding the inhaler upright with your thumb on the base, below the mouthpiece.
- Place the mouthpiece between your teeth and close your lips firmly around it. Do not bite the mouthpiece.
- Breathe in slowly through your mouth. Just as you begin to breathe in, press down firmly on the top of the canister to release one dose. Continue to breathe in slowly and deeply.
- Hold your breath for about 10 seconds, or as long as comfortable, then remove the inhaler from your mouth and breathe out slowly.
- If a second puff is needed, wait approximately 30 seconds before repeating from step 2.
- Replace the mouthpiece cap after use to protect against dust.
Check your technique in front of a mirror the first few times. If you see mist escaping from the top of the inhaler or from the sides of your mouth, you may need to adjust your coordination. Practice the timing of pressing the canister and breathing in until you get it right.
Cleaning the Inhaler
To prevent the inhaler from becoming blocked, clean it at least once a week. Remove the mouthpiece cap and wipe the inside and outside of the mouthpiece and the plastic actuator with a dry cloth or tissue. Never remove the metal canister from the plastic housing, and never put the metal canister in water. Replace the mouthpiece cap after cleaning.
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 normal schedule. Do not take a double dose to make up for the one you missed, as this increases the risk of side effects such as palpitations, tremor, and headache.
Overdose
If you accidentally take more Serevent Evohaler than prescribed, you may experience a faster heartbeat than usual, shakiness, dizziness, headache, muscle weakness, or joint pain. These effects are typically self-limiting but can be uncomfortable. If you take significantly more than your prescribed dose, or if a child accidentally uses the inhaler, seek medical advice promptly. Contact your local poison control centre or emergency department for further guidance.
There is no specific antidote for salmeterol overdose. Treatment is supportive and symptomatic. In hospital settings, cardiac monitoring may be performed, and the use of cardioselective beta-blockers may be considered cautiously in severe cases, though this requires careful assessment in patients with underlying airway disease.
What Are the Side Effects of Serevent Evohaler?
Like all medicines, Serevent Evohaler can cause side effects, although not everyone experiences them. Your doctor will prescribe the lowest effective dose to minimise the risk of side effects. Most side effects are mild and tend to decrease after the first few days or weeks of regular use as your body adjusts to the medicine. Below is a comprehensive guide to the reported side effects, organised by frequency.
Common
May affect up to 1 in 10 people
- Muscle cramps
- Tremor (shaking), especially of the hands — more common at doses above 50 mcg twice daily
- Palpitations (awareness of heartbeat)
- Headache
Uncommon
May affect up to 1 in 100 people
- Skin rash
- Tachycardia (rapid heart rate) — more common at higher doses
- Nervousness or feeling anxious
Rare
May affect up to 1 in 1,000 people
- Dizziness
- Difficulty sleeping (insomnia)
- Hypokalaemia (low blood potassium) — may cause symptoms such as irregular heartbeat, muscle weakness, or cramps
Very Rare
May affect up to 1 in 10,000 people
- Paradoxical bronchospasm — worsening of breathing or wheezing immediately after inhaling. Discontinue Serevent, use your rescue inhaler, and seek immediate medical attention.
- Cardiac arrhythmias (including atrial fibrillation, supraventricular tachycardia, and extrasystoles)
- Hyperglycaemia (raised blood sugar) — diabetic patients may need more frequent glucose monitoring
- Mouth and throat irritation
- Nausea
- Joint pain, chest pain
- Allergic reactions — sudden difficulty breathing, wheezing, swelling of the face, lips, tongue, or throat, hives, or itching. Seek immediate medical help.
Contact a doctor or go to the emergency department immediately if you experience: sudden difficulty breathing after using Serevent, swelling of your face or throat, severe allergic reaction, or if your breathing does not improve or gets worse despite using your rescue inhaler. Paradoxical bronchospasm (breathing getting worse immediately after using the inhaler) is rare but requires urgent attention.
The tremor and palpitations associated with salmeterol are a pharmacological consequence of beta-2 receptor stimulation and are dose-related. They are most commonly reported in patients taking higher doses (more than 2 inhalations twice daily) and typically diminish over the first 1–2 weeks of treatment as tolerance develops. If these symptoms are persistent or bothersome, your doctor may consider reducing the dose or adjusting your treatment regimen.
Hypokalaemia is a potential class effect of all beta-2 agonists. It is typically subclinical at recommended doses but may become clinically relevant in patients who are also taking diuretics, theophylline, or systemic corticosteroids. Your doctor may monitor your potassium levels, especially if you have underlying cardiac disease or are taking multiple medications that can lower potassium.
If you experience any side effects not listed here, or if any side effects become serious, inform your doctor or pharmacist. Reporting suspected adverse reactions after a medicine has been authorised is important for ongoing monitoring of its benefit-risk profile.
How Should You Store Serevent Evohaler?
Proper storage of your inhaler is important to ensure the medicine remains effective and safe throughout its shelf life. The pressurised metal canister contains the medicine under pressure, so it requires careful handling and storage.
- Temperature: Store at or below 30°C (86°F). Do not refrigerate or freeze.
- Heat exposure: Never expose the canister to temperatures above 50°C (122°F). Do not leave it in direct sunlight, on a car dashboard, or near radiators or other heat sources.
- Physical damage: Do not puncture, crush, or burn the canister, even when it appears to be empty. The contents are under pressure and may explode if damaged or heated.
- Mouthpiece cap: Always replace the mouthpiece cap immediately after use to prevent dust and debris from entering the inhaler. Press the cap firmly into place until you hear a click.
- Children: Keep the inhaler out of the sight and reach of children.
- Expiry date: Do not use the inhaler after the expiry date printed on the label and carton (after EXP). The expiry date refers to the last day of that month.
Do not dispose of medicines via wastewater or household waste. Return unused or expired inhalers to your pharmacist for proper disposal. Metered-dose inhalers contain fluorinated greenhouse gases (HFA 134a), and correct disposal helps minimise environmental impact.
What Does Serevent Evohaler Contain?
Serevent Evohaler has a straightforward formulation with minimal excipients. The active ingredient is salmeterol in the form of salmeterol xinafoate. The xinafoate salt form was selected for its favourable physicochemical properties that enable consistent dose delivery from the pressurised inhaler device.
- Active substance: Salmeterol (as xinafoate) — 25 micrograms per metered dose
- Excipient: Norfluran (HFA 134a) — hydrofluoroalkane propellant
The medicine is presented as a whitish suspension inside a pressurised aluminium canister fitted into a plastic actuator with a mouthpiece. Each canister provides 120 metered doses. There are no additional preservatives, colourants, lactose, or other common excipients, making this formulation suitable for patients with lactose intolerance — unlike some dry powder inhalers that contain lactose as a carrier.
This medicine contains a fluorinated greenhouse gas. Each inhaler contains approximately 12 g of HFC-134a (norfluran), which has a global warming potential (GWP) of 1,430. This is equivalent to approximately 0.0172 tonnes of CO2 per inhaler. Pharmaceutical companies are actively developing lower-GWP propellant alternatives for future inhaler formulations.
Frequently Asked Questions About Serevent Evohaler
Serevent Evohaler is a long-acting bronchodilator (LABA) used for prevention, not rescue. It takes 10–20 minutes to start working and provides bronchodilation for at least 12 hours. In contrast, a rescue inhaler like salbutamol (Ventolin) works within 1–3 minutes but only lasts 4–6 hours. Serevent is taken regularly twice daily to prevent symptoms, while a rescue inhaler is used as needed for sudden breathing difficulties. You should always carry your rescue inhaler alongside Serevent.
For asthma, Serevent Evohaler must always be used together with an inhaled corticosteroid (ICS). International guidelines from GINA strongly advise against using a LABA like salmeterol without an ICS, as this has been associated with an increased risk of serious asthma-related events. For COPD, salmeterol may be used as monotherapy in some cases, but your doctor will determine the appropriate treatment plan based on your individual needs.
Serevent Evohaler typically begins to work within 10 to 20 minutes after inhalation. However, it is not designed for immediate relief of acute symptoms — use your rescue inhaler (such as salbutamol) for that purpose. The full preventive benefit builds over the first few days of regular use. You should notice improved breathing and fewer symptoms from the first day, with continued improvement as you maintain the twice-daily regimen.
If you miss a dose, take it as soon as you remember. However, if it is almost 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 missed one. Taking doses too close together increases the risk of side effects such as rapid heartbeat and tremor. Try to set reminders or take your doses at the same times each day (e.g., morning and evening) to establish a consistent routine.
There is limited clinical data on using salmeterol during pregnancy. If you are pregnant, planning a pregnancy, or breastfeeding, consult your doctor before using Serevent Evohaler. Your doctor will weigh the benefits of controlling your asthma against any potential risks. Importantly, uncontrolled asthma during pregnancy can also pose serious risks to both mother and baby, so it is essential not to stop treatment without medical advice. International guidelines recommend that asthma should be well controlled throughout pregnancy.
Serevent Evohaler can be used by children aged 4 years and older for the prevention of asthma symptoms. The standard dose for children aged 4–12 is 2 puffs twice daily. It is not recommended for children under 4 years of age. A spacer device may make it easier for children to use the inhaler effectively. Children should always use Serevent together with an inhaled corticosteroid, and treatment should be supervised by a doctor experienced in managing childhood asthma.
References
- Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention, 2024 Update. Available at: ginasthma.org
- European Medicines Agency (EMA). Serevent Evohaler — Summary of Product Characteristics (SmPC). EMA Authorisation.
- British National Formulary (BNF). Salmeterol. National Institute for Health and Care Excellence (NICE). Available at: bnf.nice.org.uk
- World Health Organization (WHO). WHO Model List of Essential Medicines, 23rd List, 2023.
- Nelson HS, et al. The Salmeterol Multicenter Asthma Research Trial (SMART): a comparison of usual pharmacotherapy for asthma or usual pharmacotherapy plus salmeterol. Chest. 2006;129(1):15–26. doi:10.1378/chest.129.1.15
- Stempel DA, et al. Serious asthma events with fluticasone plus salmeterol versus fluticasone alone. N Engl J Med. 2016;374(19):1822–1830. doi:10.1056/NEJMoa1511049
- Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for the Diagnosis, Management, and Prevention of COPD, 2024 Report.
- British Thoracic Society (BTS) / Scottish Intercollegiate Guidelines Network (SIGN). British Guideline on the Management of Asthma, 2019 Update.
- Cazzola M, et al. Pharmacology and therapeutics of bronchodilators. Pharmacological Reviews. 2012;64(3):450–504. doi:10.1124/pr.111.004580
- Calverley PMA, et al. Salmeterol and fluticasone propionate and survival in chronic obstructive pulmonary disease (TORCH study). N Engl J Med. 2007;356(8):775–789. doi:10.1056/NEJMoa063070
Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, comprising board-certified physicians specialising in pulmonology, respiratory medicine, and clinical pharmacology. All content follows international clinical guidelines (GINA, GOLD, BTS/SIGN, ERS/ATS) and the GRADE evidence framework.
Written by specialist physicians with expertise in respiratory medicine and inhaled therapies, based on the approved Summary of Product Characteristics and international clinical guidelines.
Independently reviewed by the iMedic Medical Review Board to ensure accuracy, completeness, and adherence to evidence-based medicine standards.
Evidence Level 1A where available, based on systematic reviews and meta-analyses of randomised controlled trials. All claims referenced to peer-reviewed sources.
No pharmaceutical company funding, sponsorship, or advertising. All content is independently produced without commercial influence or conflict of interest.
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