Hi thanks for contacting HCM I Dr Kumar Abhishek any drugcan cuase adverse drugreaction in form of allergic reaction in skin. you alredy taken z pak before , i.e., azithromycine and no issues. but this time you had so i also guess it is due to Tamiflu (Oseltamivir Phosphate ). If itching is mild and mild redness in skin take Tabelet Levocetrizine 5 mg at bed time and consult treating doctor immediatly. Here is the some common side effects Oseltamivir are:- Nausea, vomiting, diarrhea, abdominal pain, and headache. Some Neuropsychiatric side effects - nervousness, aggression, hallucinations, psychosis, suicide ideation and paranoia. Azithromycine side effect:- nausea, diarrhea , vomiting , stomach pain , headache fast, pounding, or irregular heart beat dizziness , fainting ,rash , hives , itching , wheezing or difficulty breathing or swallowing swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs hoarseness ,mouth sores yellowing of the skin or eyes extreme tiredness unusual bleeding or bruising lack of energy loss of appetite pain in the upper right part of the stomach flu-like symptoms dark-colored urine blisters or peeling of the skin , unusual muscle weakness or difficulty with muscle control Call your doctor if you have any unusual problems while taking these medication. Thank You