Can I take both pills at the same time?
Plan B comes in a blister package containing two pills of a progestin (levonorgestrel). According to the FDA, you should take one pill immediately (after unprotected or inadequately protected sex) and the second one 12 hours later. There is evidence that taking both of the pills together also seems to be effective, unless it causes you to throw up within one hour of ingestion. If this happens, take something to prevent the nausea and then take another pill. Obviously it’s always preferable to take any medication according to the prescribing instructions.
What if I don't take the second pill after 12 hours?
Plan B appears to work even if you wait 24 hours to take the second pill. But you really should make the small effort to take that second pill by then.
What if I need to take Plan B more than once in the same menstrual cycle?
I'd hope you'd learn from your first experience, but Plan B appears to be safe and effective if you have unprotected sex for a second time during the same cycle.
How long can I wait after sex and still have Plan B protect me against pregnancy?
The sooner you take it the better. The risk of pregnancy for the one episode of unprotected intercourse is 0.5 percent if the pill is taken within 12 hours; the risk increases to 4 percent if Plan B is started 72 hours after exposure. The FDA approved Plan B to be taken up to 72 hours after exposure, but some studies have found it can reduce pregnancy rates even if taken 120 hours after having sex. In general, when compared to a placebo, Plan B prevents 80 percent of pregnancies if taken in the “up to 72 hour” time frame.
Will Plan B cause my period to come early or late?
It may come early — around 85 percent of women who take Plan B get their next period before expected. Fifteen percent find that their period is a week late. If your period is more than a week late, consider taking a home pregnancy test.
What if you're already pregnant when you take Plan B?
Research has shown that taking progestin-containing contraceptives during pregnancy have minimal effects on the pregnancy. So, it's doubtful that Plan B would cause a problem; though there haven't been any large studies assessing Plan B’s affects on pregnancy.
Are there any contraindications to taking Plan B?
You shouldn’t take it (of course) if you are already pregnant or you are allergic to the progestin. Plan B does not have an adverse effect on women who are breastfeeding or who have a history of cardiovascular disease, liver disease, or migraines.
Can I get Plan B if I can't prove that I'm over 18?
Yes, but you need a doctor's prescription. If you're younger than 18, sexually active, and you're not using reliable contraceptives, I strongly suggest that you get a Plan B prescription in advance and keep it "just in case."
Dr. Reichman’s Bottom Line: Plan B works, it's safe, effective and available over the counter, but it should be used appropriately.
Dr. Judith Reichman, the TODAY show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of HarperCollins.
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.