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Loratadine (Clarityn): Uses, Dosage & Side Effects

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 3 minutes read

Loratadine is a type of over-the-counter medicine known as a non-drowsy antihistamine. It is used in adults and children aged 2 years and above to relieve the symptoms of allergies in various allergic conditions, including hay fever, insect bites, pet allergies, food allergies, contact dermatitis and atopic eczema.

Loratadine helps relieve itching, sneezing, runny nose, skin rash and red/itchy/watery eyes. It is available in tablets, orodispersible tablets (they melt in your mouth) and oral liquid forms. Clarityn is a branded version of loratadine.

Even though loratadine is classed as a non-drowsy antihistamine, it can still cause drowsiness in some people. If you do experience drowsiness, it is advised that you avoid driving or drinking alcohol.

Doctor’s advice

How much should I take

Adults, children over 12 and children aged 2 - 12 (who weigh 31 kg or more) are recommended to take 10mg (1 tablet or 10ml liquid) once a day.

Children aged 2 - 12 (who weigh less than 31 kg) are recommended to take 5mg (5ml liquid) once a day.

How does Loratadine work?

During an allergic reaction, your immune system releases a chemical called histamine, which is responsible for the symptoms of an allergy. Antihistamines work by opposing the actions of histamine by stopping histamine binding to its target sites in the body.

The chemical structure of non-drowsy antihistamines makes them less likely to enter the brain through what is known as the blood-brain barrier. This makes them less likely to cause drowsiness compared to other antihistamines.

Pharmacist recommended products

Who should not take the medication?

Loratadine is not suitable for everyone. You should not take loratadine if you have previously had an allergic reaction to loratadine, desloratadine (a similar medicine) or another ingredient listed in the medicine. Loratadine should not be given to children under 2 years of age.

You should speak with your doctor before taking loratadine if you have liver or kidney problems, are pregnant or breastfeeding, have epilepsy or are at risk of having convulsions, have a metabolic disorder called porphyria, are due to have an allergy skin test, have absorption problems, or are intolerant to lactose or other sugars, as it may not be suitable for you. If you are pregnant or breastfeeding, we have a guide on taking antihistamines in pregnancy and breastfeeding.

Diabetics or people with phenylketonuria need to be careful when taking liquid and orodispersible tablet forms of loratadine as they may contain sugar or aspartame. It may be best for them to avoid these formulations.

Loratadine can interact with other medicines such as betahistine, monoamine oxidase inhibitors, dalteparin and ritonavir. If you take any prescription, over-the-counter or herbal medicines we recommend you should speak with your doctor or pharmacist to check they are safe to take alongside loratadine.

Are there any side effects?

Not everyone will experience side effects but common ones include nervousness (particularly in children), headache, drowsiness, increased appetite and insomnia.

As with all medications, there is the potential for serious side effects, such as an allergic reaction. You should stop taking loratadine and seek urgent medical attention if you develop a skin rash, shortness of breath, wheezing, tightness in your chest or throat or swelling of your tongue, mouth, lips, face or throat.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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