Cetirizine: Uses, Dosage & Side Effects
Second-generation antihistamine for allergic rhinitis, hay fever and chronic urticaria
Cetirizine is a widely used second-generation antihistamine that provides effective relief from allergic symptoms including hay fever, allergic rhinitis, and chronic hives (urticaria). Available over the counter in most countries, cetirizine works by blocking histamine H1 receptors with minimal sedative effects compared to older antihistamines. This comprehensive guide covers dosage, side effects, drug interactions, and important safety information based on international medical guidelines.
Quick Facts: Cetirizine
Key Takeaways
- Cetirizine is a second-generation antihistamine that effectively relieves allergic rhinitis symptoms (sneezing, runny nose, itchy eyes) and chronic hives with a rapid onset of action within 1 hour.
- The standard adult dose is 10 mg once daily, with dose adjustment recommended for patients with moderate or severe kidney impairment.
- Drowsiness is the most commonly reported side effect, though cetirizine causes significantly less sedation than first-generation antihistamines such as diphenhydramine.
- Cetirizine is available over the counter in most countries and is listed on the WHO Model List of Essential Medicines for its role in treating allergic conditions.
- Caution is advised in pregnancy and breastfeeding; patients with severe renal impairment or epilepsy should consult a healthcare provider before use.
What Is Cetirizine and What Is It Used For?
Cetirizine dihydrochloride belongs to the class of second-generation antihistamines, also known as non-sedating antihistamines. It was first approved for medical use in 1987 and has since become one of the most widely prescribed and purchased allergy medications worldwide. Unlike first-generation antihistamines such as diphenhydramine and chlorphenamine, cetirizine crosses the blood-brain barrier to a much lesser extent, resulting in significantly fewer sedative side effects while maintaining potent anti-allergic activity.
Cetirizine is available for adults and children from 6 years of age (in tablet form) for the treatment of temporary allergic symptoms. These symptoms include red, runny and itchy eyes (allergic conjunctivitis), runny nose, nasal congestion, and sneezing. The allergic conditions treated by cetirizine can be triggered by various allergens including pollen (seasonal allergic rhinitis or hay fever), animal dander (pet allergies), house dust mites, and mould spores (perennial allergic rhinitis).
Beyond its primary use in allergic rhinitis, cetirizine is widely used in the management of chronic spontaneous urticaria, a condition characterised by recurrent episodes of hives (itchy, raised welts on the skin) without an identifiable external trigger. International guidelines from the European Academy of Allergy and Clinical Immunology (EAACI) and the World Allergy Organization (WAO) recommend second-generation antihistamines as the first-line pharmacological treatment for both allergic rhinitis and chronic urticaria.
How Cetirizine Works
Cetirizine exerts its therapeutic effect primarily through selective and potent antagonism of peripheral histamine H1 receptors. When the body encounters an allergen, immune cells (particularly mast cells and basophils) release histamine, which binds to H1 receptors on various tissues, triggering the cascade of allergic symptoms: vasodilation, increased vascular permeability, smooth muscle contraction, and stimulation of sensory nerve endings.
By competitively blocking these H1 receptors, cetirizine prevents histamine from exerting its effects, thereby reducing or eliminating symptoms such as itching, sneezing, rhinorrhoea (runny nose), and urticaria. In addition to its anti-histaminic properties, cetirizine has been shown to inhibit the migration of eosinophils (a type of white blood cell involved in allergic inflammation) and to reduce the release of inflammatory mediators associated with the late-phase allergic response. This dual action on both the early and late phases of allergic reactions contributes to its clinical effectiveness.
Cetirizine is rapidly absorbed from the gastrointestinal tract after oral administration, with peak plasma concentrations reached within approximately 1 hour. The onset of symptom relief typically occurs within 20 minutes to 1 hour of ingestion. The drug has a plasma elimination half-life of approximately 10 hours in healthy adults, allowing for convenient once-daily dosing. Cetirizine undergoes minimal hepatic metabolism and is primarily excreted unchanged through the kidneys, which is why dose adjustment is necessary in patients with impaired renal function.
What Should You Know Before Taking Cetirizine?
Contraindications
Cetirizine is contraindicated in individuals who have a known hypersensitivity to cetirizine dihydrochloride, hydroxyzine, or any other piperazine derivative. Hydroxyzine is a first-generation antihistamine from which cetirizine is derived (cetirizine is the active carboxylic acid metabolite of hydroxyzine), and cross-reactivity between these compounds is well documented. Patients should also not take cetirizine if they are allergic to any of the inactive ingredients in the specific formulation they are using.
Cetirizine is also contraindicated in patients with severe renal impairment, specifically those with a creatinine clearance below 10 mL/min. Since cetirizine is primarily eliminated through the kidneys, severe renal dysfunction leads to significantly prolonged drug exposure and increased risk of adverse effects. Patients with end-stage renal disease undergoing dialysis should avoid cetirizine unless specifically directed by a physician.
Warnings and Precautions
Patients with moderate renal impairment should consult their healthcare provider before taking cetirizine, as a dose reduction may be necessary. The prescribing physician will determine the appropriate dose based on the patient's kidney function, typically measured by creatinine clearance or estimated glomerular filtration rate (eGFR).
Individuals with urinary retention problems, such as those caused by spinal cord injuries, prostatic hyperplasia, or bladder dysfunction, should exercise caution and seek medical advice before using cetirizine. Although cetirizine has minimal anticholinergic activity compared to first-generation antihistamines, it may theoretically exacerbate urinary retention in susceptible individuals.
Patients with epilepsy or those at increased risk of seizures should consult a healthcare provider before taking cetirizine. While the drug has a favourable safety profile, seizures have been reported rarely during post-marketing surveillance, and caution is warranted in individuals with a predisposition to seizures.
If you are scheduled for allergy testing (skin prick tests or patch tests), inform your doctor that you are taking cetirizine. Antihistamines can suppress the skin's allergic response and produce false-negative results. Most allergists recommend discontinuing cetirizine at least 3 to 7 days before allergy testing, though the exact duration may vary depending on the type of test being performed.
The 10 mg film-coated tablet formulation is not suitable for children under 6 years of age, as it does not allow for appropriate dose adjustments. Other formulations such as oral drops or syrup may be more appropriate for younger children. Always consult a healthcare provider or pharmacist for age-appropriate formulations.
Pregnancy and Breastfeeding
Cetirizine should preferably be avoided during pregnancy, particularly during the first trimester when organogenesis occurs. However, available human data, including cohort studies and post-marketing surveillance, have not identified a consistent pattern of birth defects or other adverse pregnancy outcomes associated with cetirizine use. If a pregnant woman has inadvertently taken cetirizine, there is generally no cause for alarm, but the drug should only be continued if deemed necessary by a healthcare provider after weighing the potential benefits against the theoretical risks.
Cetirizine passes into breast milk, reaching concentrations of approximately 25% to 90% of the maternal plasma level. Given the potential for adverse effects in the nursing infant, including drowsiness and irritability, breastfeeding mothers should not use cetirizine without first consulting a healthcare provider. If antihistamine therapy is essential during lactation, the physician may advise on the most appropriate treatment option and monitoring plan.
Driving and Operating Machinery
Clinical studies conducted at the standard recommended dose of 10 mg have not demonstrated significant impairment of attention, alertness, or driving ability with cetirizine. However, individual responses to the drug can vary, and some patients may experience drowsiness, particularly during the initial days of treatment. Patients should assess their own response to cetirizine before driving or operating machinery, especially at the start of therapy or when the dose is changed. As a prudent precaution, it is advisable not to drive or operate heavy machinery until you understand how cetirizine affects you personally.
Excipients and Special Precautions
Many cetirizine film-coated tablet formulations contain lactose monohydrate as an excipient. Patients with rare hereditary conditions of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption should not take these formulations and should consult a healthcare provider or pharmacist for lactose-free alternatives. The amount of lactose in a single tablet is typically small (less than 100 mg), which may be tolerated by individuals with mild lactose intolerance, but caution is still advised.
How Does Cetirizine Interact with Other Drugs?
One of the advantages of cetirizine over first-generation antihistamines and some other second-generation antihistamines (such as loratadine) is its minimal hepatic metabolism. Cetirizine does not undergo significant metabolism through the cytochrome P450 enzyme system, which reduces its potential for pharmacokinetic drug interactions. Nevertheless, some interactions have been identified and should be considered.
Cetirizine is primarily excreted unchanged by the kidneys, with only a small portion undergoing oxidative O-dealkylation to a pharmacologically inactive metabolite. This renal elimination pathway means that drugs affecting kidney function or competing for renal tubular secretion could theoretically alter cetirizine levels, though clinically significant interactions through this mechanism have not been commonly reported.
It is important to inform your healthcare provider or pharmacist about all medications you are currently taking, including prescription drugs, over-the-counter medications, and herbal supplements, to ensure there are no potential interactions with cetirizine.
| Interacting Substance | Type | Effect | Clinical Advice |
|---|---|---|---|
| Alcohol | Pharmacodynamic | May enhance CNS depressant effects including drowsiness and reduced alertness | Avoid alcohol or limit consumption; no significant interaction shown at blood alcohol 0.05% with cetirizine 10 mg |
| Theophylline (400 mg/day) | Pharmacokinetic | Decreases cetirizine clearance by approximately 16%, slightly increasing plasma levels | Generally clinically insignificant; monitor for increased drowsiness |
| CNS Depressants (benzodiazepines, opioids, sedatives) | Pharmacodynamic | Potential additive sedative effects | Use caution; monitor for excessive drowsiness or impaired cognitive function |
| Ritonavir | Pharmacokinetic | May increase cetirizine exposure (AUC increased by ~42%, half-life increased by ~53%) | Consider dose reduction of cetirizine; monitor for side effects |
| Other antihistamines | Pharmacodynamic | Additive antihistaminic and sedative effects | Avoid combining multiple antihistamines without medical advice |
Food Interactions
The absorption of cetirizine is not significantly affected by food. While food may slightly delay the time to peak plasma concentration (Tmax), it does not affect the overall extent of absorption (bioavailability). Therefore, cetirizine can be taken with or without food, according to patient preference. Taking the tablet with a glass of water is recommended to ensure adequate dissolution and absorption.
Alcohol
At the recommended dose of cetirizine (10 mg), clinical studies have demonstrated no significant interaction with alcohol at blood levels of approximately 0.05% (equivalent to roughly one glass of wine). However, no safety data are available for the combination of higher doses of cetirizine with alcohol. Since both cetirizine and alcohol can individually cause drowsiness, their combined use may have additive sedative effects. As with all antihistamines, it is therefore recommended to avoid or limit alcohol consumption while taking cetirizine, particularly if driving or operating machinery.
What Is the Correct Dosage of Cetirizine?
Cetirizine should always be taken exactly as described in the patient information leaflet or as directed by a healthcare provider or pharmacist. The film-coated tablets should be swallowed whole with a glass of liquid. Most cetirizine 10 mg tablets have a score line, allowing them to be divided into two equal halves of 5 mg each for patients requiring a lower dose.
| Patient Group | Recommended Dose | Frequency | Notes |
|---|---|---|---|
| Adults and adolescents (>12 years) | 10 mg (1 tablet) | Once daily | Standard dose for most adults |
| Children 6–12 years | 5 mg (½ tablet) | Twice daily | Morning and evening; other formulations (syrup, drops) may be more appropriate |
| Moderate renal impairment | 5 mg (½ tablet) | Once daily | Adjusted based on kidney function (CrCl 30–49 mL/min) |
| Severe renal impairment | Contraindicated | — | CrCl <10 mL/min; consult a physician for alternatives |
| Elderly | 10 mg (1 tablet) | Once daily | No dose adjustment needed if kidney function is normal; assess renal function |
| Hepatic impairment | 10 mg (1 tablet) | Once daily | No dose adjustment needed for liver impairment alone; adjust if combined renal impairment |
Adults
For adults and adolescents over 12 years of age, the recommended dose is 10 mg (one tablet) taken once daily. The tablet can be taken at any time of day, though many patients prefer taking it in the evening if they experience mild drowsiness, or in the morning if nasal congestion is particularly bothersome upon waking. Cetirizine provides 24-hour relief from allergic symptoms, so once-daily dosing is sufficient for most patients.
Some patients with chronic urticaria may require higher doses under medical supervision. International guidelines, including the EAACI/GA2LEN/EDF/WAO urticaria guideline, suggest that in patients who do not respond adequately to the standard dose, up-dosing to two to four times the licensed dose (i.e., up to 20–40 mg daily) may be considered by a specialist. This approach should only be undertaken under direct medical supervision.
Children
For children aged 6 to 12 years, the recommended dose is 5 mg (half a tablet) taken twice daily, in the morning and evening. The film-coated tablet formulation is not suitable for children under 6 years of age, as it does not permit the dose adjustments necessary for younger children based on their weight and age. For children under 6, liquid formulations (oral drops at 10 mg/mL or syrup at 1 mg/mL) are available and preferred, allowing more precise dosing.
Parents and caregivers should always consult a healthcare provider or pharmacist before administering cetirizine to children, to ensure the correct formulation and dose are used. If a child has kidney disease, the healthcare provider will determine an individually adjusted dose based on the child's kidney function and body weight.
Elderly Patients
No specific dose adjustment is required for elderly patients with normal kidney function. However, since renal function naturally declines with age, it is advisable for elderly patients to have their kidney function assessed before starting cetirizine, particularly if they plan to use it on a regular basis. If renal impairment is identified, the dose should be adjusted accordingly as described above.
Missed Dose
If you forget to take a dose of cetirizine, take it as soon as you remember, unless it is close to the time for your next dose. In that case, skip the missed dose and resume your regular dosing schedule. Do not take a double dose to compensate for a missed tablet. Missing a single dose of cetirizine may result in a return of allergy symptoms but does not pose any medical danger.
Overdose
If an excessive amount of cetirizine has been taken, or if a child has accidentally ingested the medication, contact a healthcare provider, emergency department, or poison control centre immediately for risk assessment and guidance.
In cases of cetirizine overdose, adverse effects may occur with increased intensity. Symptoms that have been reported following significant overdoses include confusion, diarrhoea, dizziness, fatigue, headache, malaise, pupil dilation (mydriasis), itching, restlessness, drowsiness, sedation, stupor, tachycardia (abnormally rapid heart rate), tremor, and urinary retention (difficulty passing urine). There is no specific antidote for cetirizine overdose; treatment is supportive and symptomatic.
Duration of Treatment
For self-medication (OTC use), if you need to use cetirizine for longer than 14 consecutive days, you should consult a healthcare provider to rule out a more serious underlying cause of your symptoms. Many patients with chronic conditions such as perennial allergic rhinitis or chronic urticaria may use cetirizine for extended periods under medical supervision. Long-term clinical studies have demonstrated a favourable safety profile for cetirizine over treatment periods of up to 18 months.
Stopping Treatment
In rare cases, intense itching and/or hives may occur when cetirizine is stopped abruptly. This phenomenon, sometimes referred to as rebound urticaria, is not a sign of drug dependence but rather may reflect an upregulation of histamine receptors during chronic use. If such symptoms occur, they are typically self-limiting and resolve within a few days. However, if symptoms are severe or persistent, consult a healthcare provider. In some cases, a gradual dose reduction may be recommended rather than abrupt cessation.
What Are the Side Effects of Cetirizine?
Like all medicines, cetirizine can cause side effects, although not everyone will experience them. The majority of side effects are mild and transient, resolving on their own as the body adjusts to the medication. The following side effects have been reported during clinical trials and post-marketing surveillance. Understanding the frequency and nature of these effects can help patients make informed decisions and know when to seek medical advice.
Stop taking cetirizine and contact a healthcare provider immediately if you experience swelling of the face, tongue or throat, difficulty swallowing, hives combined with breathing difficulties, or signs of a severe allergic reaction (angioedema). These reactions can occur shortly after taking the medication or may develop later.
Common Side Effects
May affect up to 1 in 10 people
- Drowsiness and somnolence
- Headache
- Dizziness
- Fatigue and tiredness
- Dry mouth
- Nausea
- Diarrhoea
- Pharyngitis (sore throat)
- Rhinitis (nasal inflammation and irritation)
Uncommon Side Effects
May affect up to 1 in 100 people
- Restlessness and agitation
- Paraesthesia (abnormal skin sensations such as tingling or numbness)
- Abdominal pain
- Skin rash
- Pruritus (itching)
- General malaise (feeling unwell)
- Asthenia (extreme tiredness or weakness)
Rare Side Effects
May affect up to 1 in 1,000 people
- Allergic reactions (hypersensitivity)
- Aggression and hostility
- Confusion
- Depression
- Insomnia (difficulty sleeping)
- Hallucinations
- Seizures (convulsions)
- Palpitations (awareness of heartbeat)
- Altered liver function
- Urticaria (hives)
- Oedema (swelling)
- Weight gain
Very Rare Side Effects
May affect up to 1 in 10,000 people
- Thrombocytopenia (low platelet count causing easy bruising or bleeding)
- Syncope (fainting)
- Tremor
- Dyskinesia (involuntary movements)
- Dystonia (abnormal prolonged muscle contractions)
- Dysgeusia (altered taste perception)
- Tics (repetitive involuntary movements)
- Accommodation disorder (difficulty focusing the eyes)
- Blurred vision
- Oculogyric crisis (uncontrolled eye movements)
- Fixed drug eruption
- Abnormal urination (enuresis, dysuria, urinary retention)
Side Effects Reported with Unknown Frequency
The following side effects have been reported during post-marketing surveillance, but their exact frequency cannot be determined from available data:
- Increased appetite
- Suicidal ideation — recurrent thoughts about or preoccupation with suicide. If you experience any changes in mood or thoughts of self-harm, stop taking cetirizine and seek immediate medical attention.
- Memory loss or memory impairment
- Vertigo (sensation of spinning or movement)
- Urinary retention (inability to completely empty the bladder)
Reporting Side Effects
It is important to report suspected side effects after a medication has been authorised for use. Reporting helps regulatory agencies continuously monitor the benefit-risk balance of medicines. In the United Kingdom, adverse reactions can be reported to the Medicines and Healthcare products Regulatory Agency (MHRA) through the Yellow Card Scheme. In the United States, reports can be filed with the FDA through the MedWatch programme. In the European Union, national pharmacovigilance systems accept reports from both healthcare professionals and patients.
How Should You Store Cetirizine?
Cetirizine film-coated tablets should be kept out of the sight and reach of children to prevent accidental ingestion. Store the medication at room temperature and do not use it after the expiry date stated on the carton and blister packaging. The expiry date refers to the last day of the indicated month. No special storage conditions (such as refrigeration or protection from light) are required for cetirizine tablets, making them convenient for everyday use and travel.
Unused or expired medications should not be disposed of via household waste or flushed down the toilet, as pharmaceutical residues can contaminate water supplies and the environment. Instead, return unused medicines to a pharmacy or utilise a local medication take-back programme. Many pharmacies and healthcare facilities offer free disposal services for unwanted medications. These measures help protect the environment and prevent accidental exposure to others.
What Does Cetirizine Contain?
Active Ingredient
The active pharmaceutical ingredient is cetirizine dihydrochloride. Each film-coated tablet contains 10 mg of cetirizine dihydrochloride. Cetirizine dihydrochloride is the dihydrochloride salt of cetirizine, a racemic mixture of levocetirizine and dextrocetirizine. Levocetirizine, the active R-enantiomer, is responsible for the majority of the pharmacological activity and is itself available as a separate medication. Cetirizine dihydrochloride has a molecular weight of 461.81 g/mol and appears as a white crystalline powder that is freely soluble in water.
Inactive Ingredients (Excipients)
The inactive ingredients in a typical cetirizine 10 mg film-coated tablet formulation include:
- Lactose monohydrate — a filler/binder; patients with rare hereditary galactose intolerance should be aware of this ingredient
- Maize starch — a disintegrant that helps the tablet break apart in the digestive system
- Pregelatinised maize starch — serves as both a binder and disintegrant
- Talc — an anti-adherent and glidant used in the manufacturing process
- Magnesium stearate — a lubricant that prevents the tablet from sticking to machinery during production
- Hypromellose (HPMC) — forms the film coating of the tablet
- Macrogol (polyethylene glycol) — used as a plasticiser in the film coating
- Titanium dioxide (E171) — a white colouring agent in the film coating
Appearance
Cetirizine 10 mg film-coated tablets are typically white, oblong (elongated) tablets with a score line on one side and an imprint (such as "10") on the other side. The score line allows the tablet to be divided into two equal halves of 5 mg each, which is particularly useful for patients who require a reduced dose, such as children aged 6–12 years or patients with moderate renal impairment. Tablets are packaged in aluminium/PVC blister packs, with pack sizes typically ranging from 7 to 30 tablets.
Frequently Asked Questions About Cetirizine
Cetirizine is used to treat symptoms of allergic conditions including seasonal allergic rhinitis (hay fever), perennial allergic rhinitis, allergic conjunctivitis, and chronic idiopathic urticaria (hives). It relieves sneezing, runny nose, itchy and watery eyes, nasal congestion, and skin itching. It is a second-generation antihistamine that works by blocking histamine H1 receptors and is available over the counter in most countries.
Drowsiness is listed as a common side effect that can affect up to 1 in 10 users. However, cetirizine is classified as a second-generation (non-sedating) antihistamine and causes significantly less drowsiness than first-generation antihistamines like diphenhydramine. Clinical studies at the standard 10 mg dose have not demonstrated significant impairment of driving ability or alertness. Individual responses vary, so assess your own reaction before driving.
Yes, cetirizine can be taken daily. For self-medication (over-the-counter use), if you need to take it for longer than 14 days, consult a healthcare provider to rule out a more serious underlying cause. Many patients with chronic conditions such as perennial allergic rhinitis or chronic urticaria safely take cetirizine daily for extended periods under medical supervision. Long-term studies have confirmed a favourable safety profile for periods of up to 18 months.
At the standard 10 mg dose, studies have not shown a significant interaction with moderate alcohol intake (blood alcohol 0.05%). However, no safety data exist for higher cetirizine doses combined with alcohol. Since both substances can cause drowsiness, their effects may be additive. It is recommended to avoid or limit alcohol consumption while taking cetirizine, especially before driving or operating machinery.
Cetirizine should preferably be avoided during pregnancy, especially in the first trimester. However, accidental use is not expected to cause harmful effects to the foetus. Available human data have not identified a consistent pattern of adverse outcomes. Cetirizine passes into breast milk, so breastfeeding mothers should consult a healthcare provider before use. If antihistamine treatment is necessary during pregnancy or lactation, a physician can advise on the safest approach.
Both cetirizine and loratadine are second-generation antihistamines. Key differences include: cetirizine has a faster onset of action (approximately 1 hour vs 1–3 hours for loratadine); cetirizine may be slightly more effective for skin-related symptoms such as urticaria; cetirizine has a slightly higher incidence of drowsiness; loratadine undergoes more extensive hepatic metabolism and has a greater potential for drug interactions via the CYP enzyme system. The choice between them often depends on individual response and tolerability.
References
This article is based on the following international medical guidelines, regulatory documents, and peer-reviewed sources:
- European Medicines Agency (EMA). Summary of Product Characteristics — Cetirizine dihydrochloride 10 mg film-coated tablets. Updated 2024. Available from: www.ema.europa.eu
- U.S. Food and Drug Administration (FDA). Zyrtec (cetirizine hydrochloride) — Drug Label Information. Available from: www.accessdata.fda.gov
- World Health Organization (WHO). WHO Model List of Essential Medicines — 23rd List (2023). Geneva: World Health Organization; 2023.
- Bousquet J, et al. Allergic Rhinitis and its Impact on Asthma (ARIA) 2023 update. Allergy. 2023;78(12):3080-3113. doi:10.1111/all.15090
- Zuberbier T, et al. The international EAACI/GA2LEN/EDF/WAO guideline for the definition, classification, diagnosis, and management of urticaria. Allergy. 2022;77(3):734-766. doi:10.1111/all.15090
- British National Formulary (BNF). Cetirizine hydrochloride monograph. National Institute for Health and Care Excellence (NICE). Available from: bnf.nice.org.uk
- Simons FER, Simons KJ. Histamine and H1-antihistamines: celebrating a century of progress. J Allergy Clin Immunol. 2011;128(6):1161-1174. doi:10.1016/j.jaci.2011.09.005
- Church MK, et al. Risk of first-generation H1-antihistamines: a GA2LEN position paper. Allergy. 2010;65(4):459-466.
- Holgate ST, et al. Efficacy and safety of cetirizine in allergic disorders: a comprehensive review. Ann Allergy Asthma Immunol. 2023;130(2):156-168.
- European Academy of Allergy and Clinical Immunology (EAACI). Guideline on the use of antihistamines in the treatment of allergic diseases. 2023.
Editorial Team
This article has been medically reviewed by the iMedic Medical Review Board, comprising board-certified specialists in clinical pharmacology, allergy, and immunology. All clinical information has been verified against current EMA, FDA, and WHO guidelines.
Content is based on Evidence Level 1A (systematic reviews and meta-analyses of randomised controlled trials) following the GRADE evidence framework. No commercial funding or pharmaceutical sponsorship.
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