Cetirizine is in a class of drug known as an antihistamine also called anti-pruritic. Pruritus is a medical term which means itchiness. Cetirizine blocks the actions of the naturally occurring chemical substance histamine in the body. Histamine is released by mast cells when triggered by an allergen (a mild antigen). Cetirizine is less likely than some other older antihistamines in causing the side effect of drowsiness and dizziness. Cetirizine is used to treat the symptoms of allergies such as sneezing; runny nose; itching, tearing, and redness of the eyes; and hives.
Do not take cetirizine without first talking to your doctor if you have had an allergic reaction to it or to the medication hydroxyzine (Atarax, Vistaril).
Before taking cetirizine, tell your doctor if you have kidney or liver disease. You may need a dosage adjustment or special monitoring during treatment.
Cetirizine is in is not expected to be harmful to an unborn baby but this drug passes into breast milk hence, may affect a nursing baby. . Do not take cetirizine without first talking to your doctor if you are pregnant or could become pregnant during treatment and if you are breast-feeding. A lower dose of this medicine may be prescribed for people over 65 years of age, because they are more likely to experience side effects from cetirizine.
Take cetirizine exactly as instructed by your doctor. Cetirizine can be taken with or without food. If you are taking cetirizine on a regular schedule, take the missed dose as soon as you remember but do not take a double dose.
Although symptoms of a cetirizine overdose are not well known but this may include drowsiness. Nevertheless, seek emergency medical attention if any suspected overdose symptoms is experienced.
Use caution when driving, operating machinery, or performing other hazardous activities while taking cetirizine. This is due to its major side effect which is dizziness or drowsiness, so it is better to avoid the aforementioned activities that requires you to be alert and awake. The same reason why you should use alcohol cautiously. Likewise, alcohol may increase drowsiness and dizziness while taking cetirizine.
Cetirizine may increase the effects of other drugs that cause drowsiness or dizziness, including antidepressants, sedatives (used to treat insomnia), pain relievers, anxiety medicines, muscle relaxants, cough and cold medicines and other allergy medications. Tell your doctor about all medicines that you are presently taking to avoid drug interactions. Other drugs other than those listed here may also interact with cetirizine. It is suggested to your doctor before taking any prescription or over-the-counter medicines, including vitamins, minerals, and herbal products.
Cessation of cetirizine is necessary and seek emergency medical attention if you experience a rare but serious allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives). Other, less serious side effects may be more likely to occur are the following: drowsiness; dizziness;
headache; or dry mouth. Talk to your doctor about any other unusual side effect that may appear while taking cetirizine.
Cetirizine HCl is a white, crystalline powder and is water soluble. Zyrtec tablets are formulated as white, film-coated, rounded-off rectangular shaped tablets for oral administration and are available in 5 and 10 mg strengths. Inactive Ingredients: Lactose; magnesium stearate; povidone; titanium dioxide; hydroxypropyl methylcellulose; polyethylene glycol; and corn starch.
Cetirizine has the following structural formula: