Antihistamines
Like all medicines, antihistamines can have side effects. Generally, these are moresignificant with first-generation antihistamines.
For a full list of specific side effectsof your medicine, see the information leaflet that comes withyour medication.
Most information leaflets can also be found online on the Medicines and Healthcare products Regulatory Agency (MHRA) or electronic Medicines Compendium (eMC) websites.
Common side effects of first-generation antihistamines include:
It's important not to underestimate the effects of antihistamine-related drowsiness. Some first-generation antihistamines can impair co-ordination, reaction times and judgement in the same way that alcohol consumption can. Therefore you shouldn't drive oruse power tools or heavy machinery after taking a first-generation antihistamine.
Less common side effects of first-generation antihistamines include:
Rare side effects of first-generation antihistamines include:
Contact your GP if you experience these rare side effects.
Childrenhave a greater risk ofside effects from first-generation antihistamines, particularly drowsiness and impaired thinking.
Second- or third-generation antihistamines are less likely to cause drowsiness. If you find yourself feeling drowsy, don't drive, drink alcohol, or use tools or machines.
Other side effects of second- or third-generation antihistamines include:
These side effects don't usually last long and should pass quickly.
Rarer side effects include:
However, second- and third-generation antihistamines have been found to have less risk of heart problems than first-generation antihistamines.
Contact your GP if youexperience these rare side effects.
Antihistamines used to treat stomach ulcers are known as H2 receptor antagonists. Side effects of this type of antihistamine are uncommon but may include:
Yellow Card Scheme
The Yellow Card Scheme allows you to report suspected side effects from any type of medicine you're taking.
It's run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA).
See the Yellow Card Scheme website for more information.
Antihistamines are a type of medicine often used to treat a number of allergic health conditions.
Antihistamines work by stopping histamine affecting your body's cells in the usual way.
Most people are able to take antihistamines. However, antihistamines are not recommended in certain circumstances.
The effect of antihistamines can sometimes be altered when they are combined with other substances.
Like all medicines, antihistamines can have side effects. Generally, these are more significant with first-generation antihistamines.