Fenistil belongs to a group of medicines called antihistamines. They are also used for the relief of allergic symptoms such as skin rash, pruritus, hay fever, or other forms of allergic rhinitis. Fenistil Drops blocking the action of histamine - a substance secreted in the body during an allergic reaction. It relieves itching and inflammation in skin rashes, reduces swelling and relieves the symptoms of allergic rhinitis, such as the runny nose, irritation, itchy nose, and itchy eyes.