Plan B Dosage Information

There are nearly two dozen types of oral contraceptives that can be used as emergency contraception in the U.S. None of them will be at all effective unless take in the proper dosage and administered correctly. The most commonly used emergency contraception pills are POP (Progestin Only Pills), which include Plan B One Step, Levonorgestrel Tablets, Next Choice and Next Choice One Dose. Since it is the Progestin hormone that works to prevent a pregnancy, daily birth control pills containing both estrogen and progestin are also used for emergency contraception but must be administered in much higher doses than normal. COCP (Combined Oral Contraceptive Pills)usually require a dosage of 4-5 pills to attain the higher level of Progestin necessary to prevent pregnancy.

How Does a POP like Plan B Prevent Pregnancy?

Plan B One Step contains 1.5 mg of Levonorgestrel, which is synthetic Progestin. Regular daily birth control pills only contain about .1 – .15 mg of Levonorgestrel and are combined with 30 mg of Ethinyl Estradiol (synthetic Estrogen.) In high doses like the dosage contained in Plan B One Step, Progestin not only inhibits follicular development – the step of ovulation where an egg is released- but also causes cervical mucus to thicken considerably, reducing the sperm’s viability and its ability to penetrate the cervix.

Plan B Dosage Form & Administration

Plan B One Step emergency contraceptive is provided in a single, round tablet that is off-white in color and marked on one side with “G00”. The active ingredient contained in Plan B One Step is Levonorgestrel in a dosage of 1.5 mg. Just as with any emergency contraceptive pill, in order for Plan B One Step to be at its most effective it must be administered as soon as possible after unprotected sexual intercourse, at most within 72 hours subsequent to the act. Plan B One Step is taken in only one single dose of one single tablet.

*Note: The high dosage of Progestin found in the  Levonorgestrel in the Plan B One Step pill can sometimes cause mild nausea. However, if vomiting occurs within the first two hours of taking the emergency contraceptive then you should consider repeating the dose. Consult your health care provider.

Other Emergency Contraceptive Dosages

The actual amount of Levonorgestrel dosage contained in other POP emergency contraceptive pills is equal to the dosage found in Plan B One Step. However, the dosage for Next Choice and the Levonorgestrel Tablets requires that the pills be administered as one pill taken two separate times.

Cautions regarding the Plan B Dosage

Do NOT take more than one kind of emergency contraceptive pill. Different types of oral contraception can interact negatively and negate the intended effect.

Do NOT take extra doses of Plan B without physician’s recommendation subsequent to having vomited the first dose. Taking more than one Plan B One Step tablet can cause extreme nausea.


Plan B One Step contains 1.5 mg of Levonorgestrel, and should be taken in one single dose within 72 hours of unprotected sex. It can be taken at any time during your menstrual cycle, and more than once within a month’s time, but NOT more than once in the same day without physician’s advice.

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