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.
To use the morning-after pill: Follow the morning-after pill's instructions. If you use Plan B One-Step, take one Plan B One-Step pill as soon as possible and less than 72 hours after unprotected sex. If you use ella, take one ella pill as soon as possible and less than 120 hours after unprotected sex. If you vomit within two hours after taking the morning-after pill, contact your health care provider to discuss whether to repeat the dose. Don't have sex until you start another method of birth control.