Several infectious skin diseases also cause a rash. These can be caused by a number of infections with bacteria or viruses, and infestations of mites within the skin. Some infectious skin diseases, such as scabies, are caused by mites that bore into the skin surface causing irritation and a localised rash.
Now, as for your question about when to start taking oral contraceptives, there's really no hard-and-fast rule about when to start taking birth control pills. Starting in the first few days of your cycle is the surest way to prevent inadvertently taking pills while you are pregnant.
1 Start your pills today. 2  If you start your pills today, you should use a backup method of birth control (condoms with spermicide) during the first 7 days of the pill package. 3  Birth control pills will start to protect you from pregnancy after the first week, if you take them correctly. If you start your pills today, you should use a backup method of birth control (condoms with spermicide) during the first 7 days of the pill package. 2  Birth control pills will start to protect you from pregnancy after the first week, if you take them correctly.