Desloratadine: Uses, Dosage & Side Effects
Non-drowsy antihistamine for allergic rhinitis and urticaria (hives)
Desloratadine is a long-acting, non-drowsy antihistamine used to treat the symptoms of allergic rhinitis (hay fever) and urticaria (hives). As the active metabolite of loratadine, it provides effective 24-hour relief from sneezing, runny nose, itchy eyes and skin itching. Desloratadine is available over-the-counter in many countries and is generally well tolerated with a low risk of sedation.
Quick Facts
Key Takeaways
- Desloratadine is a non-drowsy antihistamine that provides 24-hour relief from allergy symptoms with a single daily dose of 5 mg.
- It is the active metabolite of loratadine, with a longer half-life of approximately 27 hours and potent anti-allergic and anti-inflammatory properties.
- Desloratadine effectively treats both allergic rhinitis (hay fever, dust mite allergy) and chronic urticaria (hives) in adults and adolescents aged 12 and over.
- Clinical studies show a side effect profile similar to placebo, with fatigue, dry mouth and headache being the most commonly reported effects.
- No significant drug interactions have been identified in clinical studies, although caution is recommended when combining with alcohol.
What Is Desloratadine and What Is It Used For?
Desloratadine belongs to the class of second/third-generation antihistamines, which are designed to provide effective allergy relief without the sedating side effects commonly associated with older antihistamines such as chlorphenamine or diphenhydramine. It works by selectively blocking H1 histamine receptors on the surface of cells throughout the body, preventing histamine from triggering the cascade of allergic symptoms that occur when the immune system overreacts to harmless substances like pollen, dust mites or pet dander.
As the primary active metabolite of loratadine (a well-established antihistamine), desloratadine is formed naturally in the body when loratadine is processed by the liver. By taking desloratadine directly, the therapeutic effect is achieved without relying on the body's metabolic conversion, which can vary between individuals due to genetic differences in liver enzymes. This pharmacological characteristic gives desloratadine a more predictable response profile compared to its parent compound.
Desloratadine has a uniquely long half-life of approximately 27 hours, which means it remains active in the body for well over a full day. This extended duration of action allows for consistent symptom control with once-daily dosing and helps maintain relief even if a dose is taken slightly late. In addition to its antihistaminic properties, desloratadine has demonstrated anti-inflammatory effects in laboratory studies, including inhibition of the release of cytokines and chemokines from mast cells and basophils, which may contribute to its clinical effectiveness.
Allergic Rhinitis
Desloratadine is approved for the relief of symptoms associated with allergic rhinitis, a condition characterised by inflammation of the nasal lining caused by an allergic reaction. This includes both seasonal allergic rhinitis (commonly known as hay fever, triggered by pollen from grasses, trees or weeds) and perennial allergic rhinitis (caused by year-round allergens such as dust mites, mould spores or animal dander). The symptoms it effectively treats include sneezing, nasal congestion, runny nose, itchy nose, itchy palate and itchy, red or watery eyes. Clinical trials have demonstrated that desloratadine significantly reduces total symptom scores compared to placebo, with improvements noticeable within the first day of treatment.
Urticaria (Hives)
Desloratadine is also indicated for the treatment of urticaria, a skin condition characterised by the development of itchy, raised welts (hives) on the skin. In chronic spontaneous urticaria, where hives persist for more than six weeks without a clearly identifiable external cause, desloratadine helps reduce the intensity of itching and decrease the size and number of hives. European and international guidelines, including those published by the European Academy of Allergy and Clinical Immunology (EAACI) and the World Allergy Organization (WAO), recommend second-generation antihistamines like desloratadine as first-line treatment for urticaria.
The symptom relief provided by desloratadine lasts throughout the day and night, helping patients maintain their normal daily activities and sleep quality. The medication typically begins to take effect within one to three hours of ingestion, with peak plasma concentrations reached at approximately three hours.
What Should You Know Before Taking Desloratadine?
Before starting treatment with desloratadine, it is important to consider several factors that may affect whether this medication is suitable for you. While desloratadine is generally well tolerated and available without prescription for most adults, certain medical conditions and circumstances require careful consideration or medical advice before use.
Contraindications
You should not take desloratadine if you have a known allergy (hypersensitivity) to desloratadine, to loratadine (its parent compound) or to any of the inactive ingredients contained in the specific formulation you are using. Inactive ingredients vary between manufacturers and may include substances such as corn starch, microcrystalline cellulose, hypromellose and various colouring agents. If you have previously experienced an allergic reaction to loratadine-based products, you should avoid desloratadine as cross-reactivity is expected due to the close chemical relationship between these two drugs.
Warnings and Precautions
Talk to your doctor, pharmacist or nurse before taking desloratadine in the following situations:
- History of seizures: If you or anyone in your family has a history of epilepsy or seizures, consult a healthcare professional before using desloratadine. While the risk is extremely low, seizures have been reported in very rare post-marketing cases.
- Kidney impairment: If you have severe kidney disease (renal impairment), your body may not clear desloratadine efficiently, which could lead to higher blood levels of the medication. Dose adjustment or medical supervision may be necessary.
- Persistent symptoms: If your symptoms do not improve after 7 days of treatment, consult a healthcare professional. If you have been using desloratadine for longer than 3 months, you should see a doctor to investigate whether your symptoms may have a different underlying cause.
Children and Adolescents
The standard 5 mg tablet formulation is intended for adults and adolescents aged 12 years and older. For children under 12 years, different formulations (oral solution, orodispersible tablets) with age-appropriate doses are available and should be used under the guidance of a healthcare provider. The oral solution (0.5 mg/ml) is available for children aged 1 year and older, and the 2.5 mg orodispersible tablet is designed for children aged 6 to 11 years. Always consult a doctor or pharmacist for dosing guidance in children.
Pregnancy and Breastfeeding
If you are pregnant, think you may be pregnant, are planning to become pregnant, or are breastfeeding, seek advice from a healthcare provider before taking desloratadine. As a precaution, the use of desloratadine is not recommended during pregnancy due to insufficient human safety data. Animal reproductive studies have not shown direct harmful effects, but the absence of comprehensive human data means that caution is warranted. Desloratadine is excreted in breast milk and therefore breastfeeding is not recommended during treatment, unless the potential benefits to the mother clearly outweigh the risks to the infant.
Driving and Operating Machinery
At the recommended dose of 5 mg, desloratadine is not expected to impair your ability to drive or operate machinery. It was specifically designed to have minimal effect on the central nervous system, as it does not readily cross the blood-brain barrier at therapeutic doses. Nevertheless, because drowsiness occurs in a small number of individuals, it is advisable to observe how you react to the medication before engaging in activities that require full mental alertness, particularly when you first start taking it.
Alcohol
Clinical studies with desloratadine at the recommended dose did not demonstrate a significant enhancement of alcohol-related impairment. However, since both desloratadine and alcohol can potentially cause drowsiness in susceptible individuals, caution is advised when consuming alcohol during treatment. It is prudent to limit alcohol intake until you are confident about how desloratadine affects you.
How Does Desloratadine Interact with Other Drugs?
One of the notable advantages of desloratadine compared to some other medications is its favourable drug interaction profile. In formal clinical interaction studies, no clinically significant interactions were observed when desloratadine was co-administered with several commonly used drugs, including ketoconazole, erythromycin, azithromycin, fluoxetine and cimetidine. While some of these drugs caused modest increases in desloratadine plasma concentrations, none produced clinically meaningful changes in the safety profile or ECG parameters (including the QT interval).
The lack of significant drug interactions is partly explained by desloratadine's metabolic pathway. Unlike some antihistamines that are heavily dependent on specific cytochrome P450 enzymes for their metabolism, desloratadine is metabolised via multiple pathways. Its primary metabolic conversion to 3-hydroxydesloratadine involves CYP3A4 and CYP2D6 enzymes, but the drug does not appear to inhibit or induce these enzymes at therapeutic concentrations, which reduces the risk of pharmacokinetic interactions.
Despite the generally favourable interaction profile, it is always important to tell your doctor or pharmacist about all medicines you are taking, including prescription drugs, over-the-counter medications, herbal supplements and vitamins. This ensures that your complete medication profile can be reviewed for any potential concerns.
| Drug | Type | Effect | Clinical Significance |
|---|---|---|---|
| Ketoconazole | CYP3A4 inhibitor (antifungal) | Increased desloratadine plasma levels | No clinically relevant effects or ECG changes |
| Erythromycin | CYP3A4 inhibitor (antibiotic) | Increased desloratadine plasma levels | No clinically relevant effects or ECG changes |
| Azithromycin | Antibiotic (macrolide) | No significant pharmacokinetic interaction | No dose adjustment needed |
| Fluoxetine | CYP2D6 inhibitor (SSRI antidepressant) | No significant pharmacokinetic interaction | No dose adjustment needed |
| Cimetidine | Non-selective CYP inhibitor (H2 blocker) | No significant pharmacokinetic interaction | No dose adjustment needed |
| Alcohol | CNS depressant | No significant enhancement of impairment at recommended dose | Caution advised; individual variation possible |
| Grapefruit juice | CYP3A4 inhibitor (dietary) | May modestly increase desloratadine absorption | Not considered clinically significant |
Desloratadine can be taken with or without food. Food does not significantly affect its absorption or clinical effectiveness. This makes it convenient for patients to integrate into their daily routine regardless of mealtimes.
What Is the Correct Dosage of Desloratadine?
Desloratadine should always be taken exactly as described in the patient information leaflet or as directed by your healthcare provider. Do not exceed the recommended dose. If you are unsure about the correct dosage, consult a doctor or pharmacist.
| Patient Group | Formulation | Dose | Frequency |
|---|---|---|---|
| Adults and adolescents (≥12 years) | Film-coated tablet | 5 mg | Once daily |
| Children 6–11 years | Orodispersible tablet | 2.5 mg | Once daily |
| Children 1–5 years | Oral solution (0.5 mg/ml) | 1.25 mg (2.5 ml) | Once daily |
| Elderly | Film-coated tablet | 5 mg | Once daily (no dose adjustment) |
| Severe renal impairment | As appropriate for age | Use with caution | Consult healthcare provider |
Adults and Adolescents (12 Years and Over)
The recommended dose for adults and adolescents aged 12 years and over is one 5 mg film-coated tablet taken once daily. The tablet should be swallowed whole with a glass of water. It may be taken at any time of day, with or without food. For optimal symptom control, try to take the tablet at roughly the same time each day. The effects last for a full 24 hours, providing continuous relief between doses.
Children
For children between 6 and 11 years of age, the recommended dose is 2.5 mg once daily, available as an orodispersible tablet that dissolves on the tongue without the need for water. For younger children aged 1 to 5 years, an oral solution containing 0.5 mg/ml desloratadine is available; the usual dose is 1.25 mg (2.5 ml) once daily. Dosing in children under 1 year is not established, and desloratadine should not be used in this age group. Always consult a healthcare provider before giving desloratadine to children.
Elderly Patients
No dose adjustment is required for elderly patients. Desloratadine 5 mg once daily is suitable for use in older adults. However, because kidney function may decline with age, elderly patients with known severe renal impairment should use desloratadine with caution and under medical supervision.
Missed Dose
If you forget to take 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 dosing schedule. Do not take a double dose to make up for a forgotten one. Given desloratadine's long half-life of approximately 27 hours, a single missed dose is unlikely to result in a complete loss of symptom control.
Overdose
In the event of an accidental overdose, no serious problems are anticipated based on available clinical data. Overdose studies have been conducted at doses up to 45 mg (nine times the standard dose) without producing significant adverse effects. If a large overdose is suspected, or if a child has accidentally consumed the medication, contact a poison control centre or seek medical attention as a precaution. There is no specific antidote for desloratadine; treatment is supportive and symptomatic. Standard measures to remove any unabsorbed drug from the stomach may be considered. Desloratadine is not removed by haemodialysis, and it is not known whether it is removed by peritoneal dialysis.
For self-medication of allergic rhinitis, consult a healthcare provider if symptoms do not improve after 7 days. For use beyond 3 months, a medical consultation is recommended to rule out other conditions. For chronic urticaria, treatment duration is determined by your doctor based on your response to therapy.
What Are the Side Effects of Desloratadine?
Like all medicines, desloratadine can cause side effects, although not everybody experiences them. In clinical studies involving adults, the overall incidence of adverse effects with desloratadine was comparable to placebo (an inactive treatment), confirming its excellent tolerability profile. The side effects listed below are based on data from clinical trials and post-marketing surveillance reports.
In very rare cases, desloratadine can cause severe allergic reactions (anaphylaxis). Stop taking the medicine and seek emergency medical help immediately if you experience difficulty breathing, wheezing, severe itching, widespread hives or swelling of the face, lips, tongue or throat.
Side Effects in Adults and Adolescents
Common
May affect up to 1 in 10 people
- Fatigue (tiredness)
- Dry mouth
- Headache
Very Rare
May affect up to 1 in 10,000 people
- Severe allergic reactions (anaphylaxis, angioedema)
- Skin rash
- Palpitations or irregular heartbeat
- Rapid heartbeat (tachycardia)
- Stomach pain, nausea, vomiting, diarrhoea
- Dizziness
- Drowsiness or sleepiness
- Difficulty sleeping (insomnia)
- Muscle pain (myalgia)
- Hallucinations
- Seizures (convulsions)
- Restlessness with increased body movement
- Liver inflammation (hepatitis)
- Abnormal liver function test results
Not Known
Frequency cannot be estimated from available data
- Abnormal behaviour or aggression
- Depression or low mood
- Dry eyes
- Unusual weakness
- Yellowing of the skin or eyes (jaundice)
- Increased skin sensitivity to sunlight (photosensitivity)
- Changes in heart rhythm (QT prolongation)
- Weight gain and increased appetite
Side Effects in Children
The side effect profile in children is generally similar to that in adults. In post-marketing reports, additional effects that have been observed in children include:
- Abnormal behaviour or aggression
- Slow heartbeat (bradycardia)
- Changes in heart rhythm
- Weight gain and increased appetite
Parents and caregivers should monitor children for any unusual behavioural changes during treatment and report any concerns to a healthcare provider promptly.
Reporting Side Effects
If you experience any side effects, whether or not they are listed above, talk to your doctor, pharmacist or nurse. You can also report suspected side effects directly to your national pharmacovigilance authority (such as the FDA MedWatch programme in the United States, the Yellow Card Scheme in the United Kingdom, or the EMA pharmacovigilance system in Europe). Reporting helps ongoing monitoring of the benefit-risk balance of medicines.
How Should You Store Desloratadine?
Proper storage of medications is essential to ensure they remain effective and safe to use. Desloratadine does not require any special storage conditions. Keep the tablets in their original blister packaging until you are ready to take them, and store at room temperature (typically below 25°C / 77°F). Protect the medication from excessive heat and humidity, and do not store it in the bathroom where moisture levels are high.
Keep desloratadine out of the sight and reach of children. The blister packaging is designed to protect the tablets, but children should never have unsupervised access to any medication.
Do not use desloratadine after the expiry date printed on the blister pack and outer carton (marked "EXP"). The expiry date refers to the last day of the indicated month. If you notice any change in the appearance of the tablets (such as discolouration or crumbling), do not take them.
Do not dispose of medicines via wastewater or household waste. Return unused or expired medications to your local pharmacy for proper disposal. This helps protect the environment from pharmaceutical contamination.
What Does Desloratadine Contain?
Understanding the full composition of your medication is important, particularly if you have known allergies or intolerances to specific pharmaceutical ingredients. The composition varies slightly between manufacturers and formulations.
Active Ingredient
The active substance in all desloratadine products is desloratadine. Each film-coated tablet contains 5 mg of desloratadine. The oral solution contains 0.5 mg of desloratadine per millilitre. Orodispersible tablets contain 2.5 mg or 5 mg of desloratadine depending on the product.
Inactive Ingredients (Excipients)
Inactive ingredients serve important functions in the formulation, including binding the tablet, controlling its release and providing a protective coating. The exact list varies by manufacturer, but a typical film-coated 5 mg tablet may contain:
- Tablet core: Corn starch, microcrystalline cellulose, hypromellose, colloidal anhydrous silica, hydrogenated vegetable oil
- Film coating: Hypromellose (E464), titanium dioxide (E171), macrogol 400 (E1521), indigo carmine (E132)
The oral solution may contain additional excipients such as sorbitol, propylene glycol, sucralose, citric acid, disodium edetate and purified water. The solution is typically clear and colourless to slightly yellow.
Desloratadine tablets and oral solution are typically lactose-free and gluten-free, but formulations vary between manufacturers. If you have known allergies or intolerances to specific excipients, check the patient information leaflet for your specific product or ask your pharmacist.
Frequently Asked Questions About Desloratadine
Desloratadine is a non-drowsy antihistamine used to relieve symptoms of allergic rhinitis (hay fever, dust mite allergy) and urticaria (hives). For allergic rhinitis, it helps with sneezing, runny or itchy nose, and itchy, red or watery eyes. For urticaria, it reduces itching and the appearance of hives. It is available over-the-counter in many countries for adults and adolescents aged 12 and over.
Desloratadine is classified as a non-sedating antihistamine and at the recommended 5 mg dose it is not expected to cause drowsiness. However, fatigue is listed as a common side effect that can affect up to 1 in 10 users. Most people do not feel sleepy, but individual responses vary. If you are unsure how desloratadine will affect you, avoid driving or operating machinery until you have assessed your personal response.
Desloratadine is the active metabolite of loratadine. When you take loratadine, your liver converts it into desloratadine. By taking desloratadine directly, the effect does not depend on liver metabolism, making the response more predictable across individuals. Desloratadine has a longer half-life (approximately 27 hours compared to 8 hours for loratadine) and may have somewhat stronger antihistaminic and anti-inflammatory properties. Both drugs are effective non-drowsy antihistamines taken once daily.
Desloratadine is not recommended during pregnancy or breastfeeding as a precautionary measure. There is insufficient human safety data for use in pregnancy, although animal studies have not shown harmful effects. Desloratadine is excreted in breast milk, so breastfeeding mothers should consult a healthcare provider before use. Your doctor can help you weigh the benefits of treatment against the potential risks.
Clinical studies at the recommended dose did not show a significant interaction between desloratadine and alcohol. However, since both substances can potentially cause drowsiness, it is prudent to exercise caution. Limit your alcohol intake, particularly when you first start treatment, and observe how you feel before combining the two. If you notice increased drowsiness, avoid further alcohol consumption while taking desloratadine.
For self-medication of allergic rhinitis, consult a doctor if symptoms do not improve after 7 days. If you have been taking desloratadine for more than 3 months, see a healthcare provider to rule out other conditions. For chronic conditions such as perennial allergic rhinitis or chronic urticaria, desloratadine can be taken daily for extended periods under medical supervision. Long-term use has been shown to be safe in clinical studies.
References
This article is based on the following peer-reviewed sources and international guidelines:
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Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, a multidisciplinary group of licensed healthcare professionals with expertise in clinical pharmacology, allergy and immunology. All content follows international medical guidelines and the GRADE evidence framework.
Authored by clinical pharmacology specialists with extensive experience in drug information and patient education materials.
Independently reviewed by the iMedic Medical Review Board, ensuring accuracy against current EMA, FDA, WHO and BNF guidelines.
Level 1A evidence based on systematic reviews, randomised controlled trials and international clinical practice guidelines.
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