Can You Take Plan B With Birth Control?

If you’re wondering, “Can you take Plan B when also on birth control?”, you’re not alone. Many people have this question. The thought of an unplanned pregnancy can be very stressful. It is that stress that causes people to think, “Should I also take Plan B?” The hormone in Plan B is levonorgestrel.

If you have had unprotected sex and have been inconsistent with how you take your birth control, then yes, you can consider also taking Plan B. The effectiveness of the pill is 99% when taken correctly, but most people do not take it correctly. The effectiveness of the birth control pill, in reality, is closer to 93%. Taking the pill correctly means that you take it everyday and do not miss a day. It also ideally means that you take the pill at the same time everyday. Some patients may experience nausea from taking Plan B plus birth control.

When Can You Take Plan B?

If you decide that you need additional protection against pregnancy, then you can purchase Plan B from a pharmacy. Remember, that in order for emergency contraception like Plan B to be effective you must take them within one to two days of unprotected sex. While Plan B can be taken up to 3 days after unprotected sex, it is most effective when taken as soon as possible.

If you are overweight, Plan B may not be as effective for you. The BMI at which the effectiveness of Plan B goes down is considered to be a BMI of 25 (or weight of 155 lb or more). The data on this is still emerging, but in these cases, your doctor may be able to offer you a copper IUD. The ability of a copper IUD to prevent pregnancy is not affected by a person’s weight at all.

Using Plan B As Birth Control

Taking Plan B as birth control is not an ideal situation. Most doctors would recommend that you have a regular form of contraception that you use as your first line of pregnancy prevention. While there are people who use Plan B multiple times in their life to prevent pregnancy, it should be ideally reserved for emergency contraception. You can take Plan B up to 3 days after unprotected sex, but it is more effective when taken earlier.

Can You Take Plan B After 4 Days?

Plan B is not considered to be effective if you wait longer than 3 days after sex to take it.

Can You Take Plan B With Birth Control: Take Home Points

Related: Is My Vagina Normal? Plus A Female Anatomy Chart

You can take Plan B with birth control, but you should discuss it with your doctor first. You may experience some side effects from the high hormone load in the body. If you are not consistent with taking your birth control, then the chances of you being pregnant after unprotected sex are higher. In this situation, Plan B could be of additional benefit. If you are very diligent about taking your birth control pills and do not miss doses, then you may not need emergency contraception like Plan B. Always talk to your doctor before taking medications!


Batur P, Kransdorf LN, Casey PM. Emergency Contraception. Mayo Clin Proc. 2016 Jun;91(6):802-7. doi: 10.1016/j.mayocp.2016.02.018. PMID: 27261868.

Slomski A. Emergency Contraception Caution for Women With Obesity.JAMA.2022;328(4):322. doi:10.1001/jama.2022.12180

Simmons KB, Edelman AB. Hormonal contraception and obesity. Fertil Steril. 2016 Nov;106(6):1282-1288. doi: 10.1016/j.fertnstert.2016.07.1094. Epub 2016 Aug 23. PMID: 27565257.

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