If you have any significant side effects, such as mental or emotional problems (such as restlessness, disorientation, or hallucinations), shaking (tremors), difficulties urinating, or a rapid or irregular heartbeat, contact your doctor straight once. These may be signs of serious problems that need to be diagnosed and treated promptly. Hydroxyzine can cause people who take it to become agitated or anxious, but this effect is usually not severe. Hydroxyzine can also cause dry mouth and drowsiness, but these effects are rarely severe. People who take hydroxyzine for long periods may find themselves slowing down on its effects, so they must continue to take it daily to stay calm and focused. The most common side effects of hydroxyzine include nausea, vomiting, diarrhea, constipation, blurred vision, dizziness, headache, depression, anxiety, nervousness, irritability, trouble sleeping, tingling sensations, rash, or urinary frequency. These are often mild symptoms that go away after you start taking the drug. But if you experience any symptoms that worry you or do not go away, tell your doctor immediately. Hydroxyzine is used to treat anxiety disorders, chronic stress, depression, obsessive-compulsive disorder (OCD), and certain other psychological conditions. It does not cure these problems but simply treats their symptoms.