Most people are able to take antihistamines. However, antihistamines are not recommended in certain circumstances.
These are explained below.
Health conditions
A number of health conditions can be made worse by taking antihistamines, or they can cause the antihistamines to react unpredictably. These include:
- asthma
- diabetes (type 1 diabetes and type 2 diabetes)
- high blood pressure
- epilepsy
- heart disease
- liver disease
- kidney disease
- an overactive thyroid gland
Before taking antihistamines, seek advice from your GP or pharmacist if you have another health condition and you are unsure whether antihistamines are suitable for you.
Pregnancy and breastfeeding
As a general rule, avoid taking any medication during pregnancy unless there’s a clear clinical need. Always check with your GP, pharmacist or midwife before taking any medication.
If you’re pregnant and feel that you need antihistamines, or you’re advised to take them by your GP, loratadine or chlorphenamine are the antihistamines considered the safest to use.
However, chlorphenamine is a first-generation antihistamine, so it may make you feel drowsy.
If you can’t take loratadine or chlorphenamine, your GP may recommend another oral antihistamine called cetirizine. Cetirizine is also considered safe to use during pregnancy.
Antihistamine eye drops and nasal sprays should be used with caution during pregnancy. Some people are allergic to antihistamine eye drops. Seek advice from your GP before using antihistamine eye drops or nasal sprays.
Most antihistamines will pass into breast milk. While this isn’t thought to be particularly harmful, it’s recommended as a precaution that you don’t breastfeed while taking antihistamines.
Children
Some antihistamines, such as alimemazine and promethazine, aren’t suitable for children under two years old. Therefore seek advice from your GP if your child is under two years old and you think that they require treatment with antihistamines.
Some antihistamines are not recommended for children with certain conditions. For example, the National Institute of Clinical Excellence (NICE) recommends that oral antihistamines should not be used routinely to treat children with atopic eczema.
Before giving your child any form of medication, always read the patient information leaflet for advice about whether the medication is suitable for them.