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Does Plan B cause side effects?
Plan B One-Step (levonorgestrel) is emergency contraception (commonly called the “morning after pill”) used as backup contraception to prevent pregnancy when taken within 72 hours after unprotected sex or when birth control fails.
Levonorgestrel is a progestin. Progestins are hormones used in many birth control pills. Although levonorgestrel and similar emergency contraception pills contain a higher dose of levonorgestrel than birth control pills, they work in a similar way to prevent pregnancy, mainly by stopping the release of an egg from the ovary.
Additionally, levonorgestrel also may prevent fertilization of an egg (the uniting of the sperm with the egg) or prevent the attachment (implantation) of a fertilized egg to the uterus (womb).
Emergency contraception pills do not work in women who are already pregnant and should not be taken during pregnancy. Most emergency contraception pills can be purchased over-the-counter or over-the-counter (OTC). Some age restrictions may apply.
Common side effects of Plan B One-Step include
- menstrual changes,
- lower stomach (abdominal) pain,
- vomiting, and
- breast pain.
Drug interactions of Plan B One-Step include drugs or herbal products that increase the activity certain liver enzymes that breakdown drugs, which may reduce blood levels of levonorgestrel and the effectiveness of Plan B One-Step.
Emergency contraception pills such as Plan B One-Step will not work if you are already pregnant and should not be used during pregnancy. Plan B One-Step is thought to enter human milk after oral administration and should be used cautiously in breastfeeding mothers.
Plan B (levonorgestrel) side effects list for healthcare professionals
Clinical Trial Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
A double-blind, controlled clinical trial in 1,955 evaluable women compared the efficacy and safety of Plan B (one 0.75 mg tablet of levonorgestrel taken within 72 hours of unprotected intercourse, and one tablet taken 12 hours later) to the Yuzpe regimen (two tablets each containing 0.25 mg levonorgestrel and 0.05 mg ethinyl estradiol, taken within 72 hours of intercourse, and two tablets taken 12 hours later).
The most common adverse events (>10%) in the clinical trial for women receiving Plan B included
- menstrual changes (26%),
- nausea (23%),
- abdominal pain (18%),
- fatigue (17%),
- headache (17%),
- dizziness (11%), and
- breast tenderness (11%).
Table 1 lists those adverse events that were reported in ≥5% of Plan B users.
Table 1: Adverse Events in ≥5% of Women, by % Frequency
|Heavier Menstrual Bleeding||13.8|
|Lighter Menstrual Bleeding||12.5|
The following adverse reactions have been identified during post-approval use of Plan B. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Abdominal Pain, Nausea, Vomiting
General Disorders and Administration Site Conditions
Nervous System Disorders
Reproductive System and Breast Disorders
What drugs interact with Plan B (levonorgestrel)?
Drugs or herbal products that induce enzymes, including CYP3A4, that metabolize progestins may decrease the plasma concentrations of progestins, and may decrease the effectiveness of progestin-only pills. Some drugs or herbal products that may decrease the effectiveness of progestin-only pills include:
- barbiturates (including primidone)
- St. John’s wort
Significant changes (increase or decrease) in the plasma levels of the progestin have been noted in some cases of co-administration with HIV protease inhibitors or with non-nucleoside reverse transcriptase inhibitors.
Concomitant administration of efavirenz has been found to reduce plasma levels of levonorgestrel (AUC) by around 50%, which may reduce the effectiveness of Plan B.
Consult the labeling of all concurrently used drugs to obtain further information about interactions with progestin-only pills or the potential for enzyme alterations.
Drug Abuse And Dependence
Levonorgestrel is not a controlled substance. There is no information about dependence associated with the use of Plan B.
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Related Disease Conditions
Birth Control Options
Birth control is available in a variety of methods and types. The method of birth control varies from person to person, and their preferences to either become pregnant or not. Examples of barrier methods include barrier methods (sponge, spermicides, condoms), hormonal methods (pill, patch), surgical sterilization (tubal ligation, vasectomy), natural methods, and the morning after pill. Side effects and risks of each birth control option should be reviewed prior to using any birth control method.
Birth Control Pill vs. Depo-Provera Shot
Birth control pills (oral contraceptives) and the Depo-Provera shot are two hormonal methods of birth control. Both methods work by changing the hormone levels in your body, which prevents pregnancy, or conception. Differences between "the pill" and "the shot." Birth control pills are available as combination pills, which contain the hormones estrogen and progestin, or mini-pills that only contain progestin. In comparison to the Depo-Provera injection, which prevents pregnancy for three consecutive months. Both methods of birth control are very effective in preventing pregnancy. Both the combination pill (if you take them as directed) and shot are up to 99% effective in preventing pregnancy. While the mini-pill is only about 95% effective in preventing pregnancy. Both methods cause weight gain, and have other similar side effects like breast pain, soreness or tenderness, headaches, and mood changes. They may lead to decreased interest in sex in some women. There are differences between the other side effects of these methods (depending upon the method) that include breakthrough bleeding or spotting, acne, depression, fatigue, and weakness. Both oral contraceptives and the Depo-Provera shot have health risks associated with them, such as, heart attack, stroke, blood clots, and cervical cancer. Birth control pills appear to increase the risk of cervical cancer. Talk with your OB/GYN or other doctor or health care professional about which birth control method is right for you.
DVT and Birth Control Pills (Oral Contraceptives)
Deep vein thrombosis (DVT) is a blood clot that has traveled deep into the veins of the arm, pelvis, or lower extremities. Oral contraceptives or birth control pills can slightly increase a woman's risk for developing blood clots, including DVT. DVT symptoms and signs in the leg include leg or calf pain, redness, swelling, warmth, or leg cramps, and skin discoloration. If a blood clot in the leg is not treated, it can travel to the lungs, which can cause a pulmonary embolism (blood clot in the lung) or post-thrombotic syndrome, both of which can be fatal if not treated immediately. Increased risk factors for DVT and birth control pills include over 40 years of age, family history, smoking, and obesity. Other medical problems that increase the risks of blood clots, for example, lung or heart disease, or inflammatory bowel disease or IBD (Crohn's disease and ulcerative colitis (UC). Other options for preventing pregnancy include IUDs, birth control shots, condoms, diaphragms, and progestin-only oral contraceptives.
Treatment & Diagnosis
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.