Updated 18 April 2017

5 things to know before taking an antihistamine

Nasal congestion, red, itchy eyes and sneezing - your allergies are flaring up again but before you take an antihistamine, make sure you know these five facts.

If you suffer from allergies, taking antihistamines may be the only way you can manage your symptoms and get through the day but have you ever stopped to think about which antihistamine you choose, when you should be taking it and when you should avoid them altogether?

Here are the answers to five common questions:

1. Will antihistamines make me drowsy?

The first antihistamines caused more drowsiness than newer versions - so much so that they were even used as sleeping pills by some. Avoid taking chlorpheniraminediphenhydraminebrompheniramine and other older antihistamines as these all have a sedating effect.

Nowadays, you don't have to avoid treating your allergies for fear that you may fall asleep at your desk. Newer antihistamines such desloratadine, fexofenadine, loratadine and cetirizine usually do not cause drowsiness, the National Institutes of Health explains.

2. Do antihistamines interfere with other medication?

Before you take antihistamines, check to see that they don't interact poorly with other medications you may be taking. Medication for depressive disorders, anxiety disorders, sleep problems and chronic pain can contain sedatives that, when taken with first generation antihistamines, may cause extreme drowsiness and impairment.

If you are being treated for any of these conditions, always check with your doctor before taking antihistamine medication.

3. Can I take antihistamines with an existing medical condition?

With certain pre-existing conditions, certain care needs to be taken antihistamine medication. People who suffer from epilepsy should avoid sedating antihistamines.

People with chronic liver disease should also consult a doctor before taking antihistamines, Bupa UK warns.

Pregnant women or women who are breastfeeding should avoid antihistamine medication entirely.

4. Do I need a prescription for antihistamines?

There are many different types of over-the-counter antihistamines. It is worth trying different brands until you find one that works for you. For people with severe allergies, a prescription antihistamine may be needed.

5. Am I taking the right antihistamine?

Antihistamines aren't all the same. Certain antihistamines will work better for particular allergies or symptoms. Ask your doctor or pharmacist for advice before choosing a product.

Many antihistamine medications include decongestants. Only take these if you are suffering from congestion as they can increase blood pressure, Reader's Digest suggests.

Read more:

Antihistamines can affect your driving

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Ask the Expert

Allergy expert

Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies.

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