Cetirizine, the generic name for Zyrtec, is an antihistamine. An antihistamine treats the symptoms associated with allergies, hives and hay fever. In addition to seasonal allergies, cetirizine can be used to treat individuals with allergies to pet dander, dust and molds. The medication helps eliminate the sneezing, runny nose and red eyes associated with allergies. Zyrtec is taken once a day, and is available as a liquid, a tablet and a chewable tablet. The tablets come in 5mg and 10mg strengths. Along with the desired effects of the medicine, there are possible unwanted side effects of cetirizine.
Common Side Effects
A common side effect of cetirizine is drowsiness. Fatigue may follow the drowsiness. Until the effects of the medicine are known, it is important to avoid driving or using heavy machinery. A headache, irritation or infection of the throat, and coughing may occur. Gastrointestinal upset symptoms include nausea, vomiting, stomach pain and diarrhea. This medicine may also cause an extremely dry mouth. Sucking on hard candy may help relieve the dry mouth feeling. These symptoms are not serious and will normally decrease with time. However, if the side effects become worse, do not go away or become bothersome, your doctor may wish to change the medication or adjust the dose.
Serious Side Effects
Some side effects of cetirizine are serious and can cause harm. The following side effects need to be brought to the attention of your doctor immediately: increase in heart rate, high blood pressure and heart palpitations. According to RxList.com, rare side effects include paralysis, deafness and pneumonia.
Overdose and Allergy
Signs of an allergic reaction to cetirizine include, but are not limited to, difficulty breathing, increase in heart rate, swelling of the face or airway, and hives. Emergency medical attention is warranted if any of these symptoms are present. According to MedlinePlus, signs of an overdose of this medication include irritability, drowsiness and restlessness. Children are more likely to experience irritability and restlessness.