What Happens When You Forget To Take Your Birth Control One Day

It's going to happen at least once when you're on the pill. The day flies by, you're super busy, and you don't realize until the next morning that you didn't take it the day before. You start to panic.

We get it. It's scary. When taken perfectly, the pill has a failure rate of 1 to 2% per year (out of 100 women, one or two will become pregnant). But when taken imperfectly — which is closer to reality — the failure rate rises to 5 to 9%, according to Drugs.com. Your chances of becoming pregnant from a missed pill depend on several factors, such as when in your cycle you missed it, whether or not you had unprotected sex around that time, and the kind of pill you're taking.

If you don't want to be one of those five to nine women, you should know what to do in the event of a missed pill. First, find out which kind of pill you're on: a progestin-only or "mini" pill; a combination pill, which contains both progestin and estrogen; an extended-cycle pill, which has 84 active tablets and seven inactive (or with a low dose of estrogen) and reduces monthly periods to four per year; or a continuous-cycle pill, which contains progestin/estrogen with no inactive or dummy tablets, eliminating periods completely. 

Missing a mini pill

The progestin-only pill has very little wiggle room timewise, and needs to be taken at the same time every single day. If it's more than three hours past the time you were supposed to take it, it's considered "missed."

That's because the hormones in the mini pill wear off much more quickly than they do in a combination pill. This drop in hormones means there's a higher risk of pregnancy, according to the Cleveland Clinic. Mini pills work by thickening the cervical mucus to prevent sperm from entering the uterus and by thinning the uterine lining so an egg can't implant (per Healthline). When one pill is missed, it can take two days for the mucus to thicken again.

What to do? Take the missed pill as soon as you remember, then continue taking it at your normal time each day, even if that means you'll have two in one day. It will take two full consecutive days of correct pill usage before you are out of danger for getting pregnant, so use nonhormonal backup contraception until then when having sex.

If you've had unprotected sex in the last five days, talk to your doctor about using emergency contraception, such as Plan B One-Step, which contains the hormone levonorgestrel to prevent pregnancy (per Drugs.com).

Missing a combination pill

When it comes to forgetting to take one combo pill, whether or not you get pregnant depends on exactly which one it is. If it's a placebo pill (one of the seven differently colored pills in your monthly pack, which contain no hormones), it won't raise your chances at all. There's no need to do anything except get back on track.

If the pill is from the first week of your pack, the chance of pregnancy is higher than if the pill is from the middle of the pack. That's because in the first week, you're just coming off the seven placebo pills, and your body is low in pregnancy-preventing hormones (per the Cleveland Clinic). The estrogen and progestin in the active combo pill work by preventing the ovaries from releasing an egg and thickening the cervical mucus so sperm can't reach the uterus (per Healthline). Without the necessary levels of those hormones, an egg can be released.

No matter where the missed pill is in the pack, take it when you remember — it's okay to have two pills in one day — then take the rest of the pack as usual. You won't need to use backup contraception if less than 48 hours has passed since your last pill. If it's been longer than that, use a nonhormonal method for seven days when having sex, recommends Drugs.com.

Missing an extended-cycle or continuous-cycle pill

In an extended-cycle pack, there are 84 active pills and seven inactive, or placebo, pills. These pills should be taken at the same time every day. If the pill you've forgotten is a placebo, you don't need to do anything to prevent pregnancy. But if you miss an active pill, take it as soon as you remember, then continue taking the pills according to your usual schedule. You may have to take two pills in one day to get back on track. There's no need to use backup contraception.

Every pill in the continuous-cycle pack is active, which means they all contain hormones, so periods are completely eliminated. Should you forget any one pill, take it as soon as it's remembered, then take one pill daily for the rest of the pack. Again, you may need to take two in one day. If you have sex in the next seven days, you must use a nonhormonal backup contraceptive method, such as condoms, to prevent pregnancy, according to Drugs.com.

Side effects of missing a birth control pill

The hormones in the pill wear off in about 36 hours (per Cleveland Clinic), so missing even one may cause physical effects. These might include light bleeding, spotting, or starting a period; menstrual cramps; nausea; and headaches or migraines due to the lower levels of estrogen (per WebMD). If you take the mini pill, you may not experience these side effects.

Of course, one major side effect of missing a pill may be ovulation and possibly pregnancy. Your chance of becoming pregnant depends on where in the pack the missed pill was (it's higher during the first week of a new pack or the week right before your period). With a combination pill, it also depends on how long it's been since the last one — if it's more than 24 hours, the risk of pregnancy rises. With a mini pill, missing just one raises the chance of becoming pregnant. To be on the safe side, you should use nonhormonal backup contraception if you miss even one pill.

If you often forget to take your pill, consider downloading a pill reminder app on your phone, such as Aavia Cycle & Period Tracker, the Birth Control Pill Reminder, or the Spot On Period Tracker, which can also prompt you to remember your pill. Or you may want to consider switching to a different form of birth control entirely — one that doesn't depend on remembering to take it every day.