"Most allergic reactions occur within hours to two weeks after taking the medication and most people react to medications to which they have been exposed to in the past. This process is called “sensitisation.” However, rashes may develop up to six weeks after starting certain types of medications. Rarely, blisters and bleeding inside the skin or the inner surfaces of the intestines may occur. Unfortunately, if it is the life threatening anaphylaxis, it could be fatal. So, it is important to educate people about these possible reactions to drugs."