Mast cells. Mast cells and basophils are generally thought to be the major sources of histamine and can themselves be modulated by histamine as they express H 1, H 2 and H 4 receptors, although how this varies between different mast-cell types is not yet clear.
3. The pill is to be taken soon after unprotected sex. It should be taken preferably within 24 hours and before 72 hours or else the pill may turn useless. 4. I-pill checks pregnancy by preventing ovulation or fertilisation or implantation of the fertilised egg. 5. I-pill is 95 per cent effective if taken in time.
The morning-after pill (also known as emergency contraception) is a safe and effective way to reduce the risk of pregnancy after unprotected intercourse. It can be started up to five days (120 hours) after unprotected sex. The brands Plan B One-Step and Next Choice are available from drugstores and health centers without a prescription for women and men 17 and older. A new brand, ella, is available by prescription only.