Cetirizine tablets and liquid are also widely available without a brand name, ie as the generic medicine. Antihistamines may oppose the effect of histamine (used to treat leukaemia) and are not recommended for people having this treatment. Antihistamines may also oppose the effect of betahistine (used to treat Ménière's disease) so this medicine is probably best avoided if you're taking betahistine.

If you forget to take a dose, take the next dose when needed provided that you only take a maximum of 1 capsule in 24 hours. Do not take a double dose. In most people Benadryl Allergy Liquid Release Capsules do not cause drowsiness. However, there are rare exceptions and you should take care when you use this product for the first time. If Benadryl Allergy Liquid Release makes you feel drowsy, do not drive or operate machinery. Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Benadryl only for the indication prescribed. People with kidney problems. A lower dose of cetirizine is often needed for people with kidney problems and Benadryl capsules cannot be split to achieve this. Other cetirizine products may be suitable - ask your doctor. Cetirizine, a human metabolite of hydroxyzine, is a potent and selective antagonist of peripheral H 1-receptors. In vitro receptor binding studies have shown no measurable affinity for other than H 1-receptors.Do not give this medication to a child younger than 2 years old. Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

In addition to its anti-H 1 effect, cetirizine was shown to display anti-allergic activities: at a dose of 10 mg once or twice daily, it inhibits the late phase recruitment of eosinophils, in the skin and conjunctiva of atopic subjects submitted to allergen challenge. In a placebo-controlled study, cetirizine given at the high daily dose of 60 mg for seven days did not cause statistically significant prolongation of QT interval. This is a medicine; Consult your doctor or pharmacist if you have an underlying medical condition, are taking any other medication or complementary therapy, or if symptoms persist.Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with cetirizine. Just because a side effect is stated here doesn't mean that all people taking this medicine will experience that or any side effect. Common side effects (affect between 1 in 10 and 1 in 100 people) Sudden onset of fever, reddening of the skin, or many small pustules (possible symptoms of Acute Generalised Exanthematous Pustulosis – AGEP) may occur within the first 2 days of treatment with this medicine. Instances of abnormal hepatic function with elevated hepatic enzymes accompanied by elevated bilirubin have been reported. Mostly this resolves upon discontinuation of the drug. Treating allergies such as hay fever, pet allergies and dust mite allergies (seasonal and perennial allergic rhinitis). Benadryl may cause blurred vision and may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.