Applies to hydroxyzine: compounding powder, intramuscular solution, oral capsule, oral suspension, oral syrup, oral tablet. General. The most commonly reported side effects included sleepiness, headache, and tiredness. Nervous system. Very common (10% or more): Sleepiness (up to 13.74%) Common (1% to 10%): Headache. Rare (0.01% to 0.1%): Convulsion, tremor. Frequency not reported. Clonidine works pretty well if you don’t have problems with nasal congestion or dry eyes. I can handle the dry eyes but not being able to breathe is something I cannot. Constipation can happen also. Reply Link. Katherine May 20, 2016, 9:33 am. Hi. I took Prozac for 15 years for depression and anxiety, I had a horrific time coming off it and it has been suggested that clonidine may aid. Hydroxyzine can also be used for the treatment of allergic conditions, such as chronic urticaria, atopic or contact dermatoses, and histamine-mediated pruritus. These have also been confirmed in both recent and past studies to have no adverse effects on the liver, blood, nervous system, or urinary tract. Hydroxyzine can provide anxiety relief until the longer-term medication starts to kick in. Either way, hydroxyzine is only taken when symptoms appear. Like all prescription medications, hydroxyzine should be taken only as your healthcare provider prescribes it, so be sure to follow the instructions on your prescription. The typical adult dosage is 50 mg to 100 mg up to 4 times daily, with or.