Hi if you are going to take cetrizine for few days, and prescribed by a doctor, yes it is okay. As you are also taking mirnite and clonazepam you may feel drowsy and sedated. So avoid driving. I see that your weight is 90 kg. Try exercise and walking as mirnite can increase your appetite. Clonazepam is safe for short term use only.

It is safe to use the above medicine. But stay in touch with your treating psychiatrist for further guidance in future.