Avoid drinking alcohol. It can increase some of the side effects of cetirizine. Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by cetirizine. Call your doctor if your symptoms do not. Before looking at the facts of mixing alcohol and Zyrtec, such as the side effects, dangers & interactions, what is Zyrtec? Zyrtec is an antihistamine with the generic name cetirizine, which is used to treat allergy-related symptoms including runny nose, itchiness, sneezing, hives and watery eyes. A 30-year-old female patient was prescribed oral cetirizine 10 mg at night for the treatment of chronic idiopathic urticaria. Within 15 min of oral ingestion of cetirizine 10 mg, the patient experienced severe pruritis and urticarial eruption all over the body. What is cetirizine. Cetirizine or cetirizine hydrochloride (cetirizine HCL) is a non-drowsy antihistamine medicine that relieves the symptoms of allergies by blocking the effects of the chemical histamine in your body. Mixing cetirizine with alcohol can cause drowsiness or make you less alert. If you take any type of tranquilizer, sedative, or sleep aid, make sure to ask your doctor before you use cetirizine. If you drink alcohol while you are on cetirizine, be aware of its effects on you and do not drink more than moderate amounts. Alcohol can increase the risk of side-effects from antihistamines. Alcohol can increase the risk of side-effects from antihistamines. You can drink alcohol in combination with cetirizine. But since both cetirizine and alcohol can have a negative effect on coordination and reaction time, it would be wise to not drink alcohol for the first few days (if you use it for a longer period of time). I still cannot post links so look up in google: Cetirizine Compositions site:freepatentsonline.com The reaction seems to be a Fischer-esterification between a carboxylic acid (Cetirizine) and alcohols. Alcohol can increase the nervous system side effects of cetirizine such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. For example, if you have a reaction to an insect bite, you may only need to take cetirizine for a day or two. You may need to take cetirizine for longer if you're taking it to prevent symptoms - for example, to stop hay fever when the pollen count is high.