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 You must get a prescription to start birth control pills, a patch, or a vaginal ring. 2  There are different options for birth control pills that range from 21 day pills to 365 day pills and have different combinations of estrogen and progestin.