hello adverse effects of cetrizine are Changes in mood, irrational behavior, depersonalization hallucinations convulsions (seizures) extreme sleepiness or unusual drowsiness fast, slow, pounding, or irregular heartbeat or pulse feeling anxious giddiness headache irritability muscle weakness or tenderness nausea restlessness shallow, irregular, fast, or slow breathing sleeplessness or trouble in sleeping abdominal and/or chest pain thirst kindly consult a physician and dermatologist to find out the actual cause of rashes.