Birth control pills are an effective, safe, and low-cost option for preventing pregnancy. As with any medication, you may experience some side effects while taking the pill.

Here’s more about why you may spot while on the pill and how to treat this side effect.

How do birth control pills work?

There are two main types of birth control pills. The first combines man-made versions of the hormones estrogen and progesterone. These are called ethinyl estradiol and progestin.

The second type of birth control pill is a progestin-only pill. It’s also called “the minipill.” Your doctor can help you decide which pill is right for you.

The combination pill works by suppressing your pituitary gland so that the release of an egg from your ovaries, or ovulation, doesn’t occur.

This pill also thickens your cervical mucus to prevent sperm from reaching any available eggs. The lining of your uterus is also altered to prevent implantation.

The minipill also alters cervical mucus and the uterine lining. The hormones can also suppress ovulation, but this is less reliable.

With perfect use, birth control pills are up to 99 percent effective in preventing pregnancy. Perfect use means that you take the pill every day at the same time. It doesn’t account for any late, missed, or skipped doses of the medication.

With typical use, which allows for some error, the pill is about 91 percent effective. For the best results, you should aim to take your birth control pills at the same time every day.

It’s important to remember that birth control pills don’t protect against sexually transmitted infections (STIs), so you should always use condoms. You should also keep up with annual well woman visits for screenings.

Side effects

The pill is a popular birth control option partly because of it’s limited side effects. Even if you do experience side effects after starting the pill, these symptoms are usually temporary.

Spotting is one such symptom. Irregular bleeding or spotting is common in the first three to four months after you start taking the pill. This should subside once your body adjusts to the medication. You may experience spotting later on if you’ve missed or skipped a dose.

If this bleeding becomes heavy, don’t stop taking your medication. Continue taking your pill as prescribed and contact your doctor.

Other side effects may include:

  • irregular bleeding
  • spotting
  • nausea
  • headaches
  • mood changes
  • tender breasts
  • weight gain or loss

Many women find that their body adjusts to the pill after a few months and symptoms subside.

What can cause spotting?

Although some women may experience spotting the entire time they’re on birth control pills, this side effect typically decreases in severity after about four months of use. In many cases, the cause of the spotting is unknown and harmless.

The estrogen in combination pills helps to stabilize the lining of the uterus. This can prevent irregular bleeding and spotting. Women who take progestin-only pills may experience more frequent spotting.

Spotting may also be caused by:

  • an interaction with another medication or supplement
  • missing or skipping doses, which causes hormone levels to fluctuate
  • vomiting or diarrhea, which can prevent proper drug absorption

It’s particularly important to pay attention to spotting if you’ve missed doses of your medication and have had unprotected sex. Irregular bleeding with cramps can also be a sign of pregnancy or miscarriage and may require medical attention.

Risk factors

Women who take progestin-only pills are at higher risk of spotting. You may have an increased risk of spotting while on the pill if you smoke cigarettes. Let your doctor know of any smoking habits before you get a prescription so you can chat about the potential complications.

Women who take continuous birth control pills may also be at a higher risk of spotting. These pills include Seasonale, Seasonique, and Quartette.

Occasionally, your doctor may advise you to take a short break from the continuous cycle of hormones to allow your body to have a short period. This may help resolve any irregular bleeding.

The pill is also associated with an increased risk of blood clotting. Blood clotting can lead to:

  • a stroke
  • a heart attack
  • a deep vein thrombosis
  • a pulmonary embolism

The overall risk for blood clotting is low unless you:

  • have high blood pressure
  • smoke
  • are overweight
  • are on bed rest for an extended period

Your doctor can help you select a birth control option with the least risk.

Talking with your doctor

Most cases of spotting while on the pill are temporary and will resolve over time. If you’re concerned, contact your doctor. Be sure to let your doctor know if you experience any of the following:

  • headaches
  • swelling in your legs
  • bruising
  • fatigue
  • irregular bleeding or spotting, especially if your bleeding is heavy

If you have unprotected sex after missing two or more pills or have sex with a partner who may have an STI, speak with your doctor.

Once you rule out any underlying causes for your irregular bleeding, your doctor may prescribe a different type of pill or form of birth control. Ask about pills that contain estrogen, since this hormone helps keep the lining of the uterus in place.

Monophasic pills keep your levels of estrogen stable over the course of the month. Multiphasic pills change the levels at different points throughout your cycle. Your body may react differently to higher or lower levels of estrogen, so only change pills under the direction of your doctor.

Alternatively, your doctor may prescribe a pill with a low dose of estrogen if you’d rather stay on a progestin-only pill. These pills are safe, and your doctor will give you instructions on when to take them for the best results.


Spotting typically resolves after the first three to four months of using birth control pills. If you’re spotting and still in this window of time, try your best to stick it out.

One of the best ways to prevent or reduce spotting while on the pill is to take your medication at the same time each day. This helps regulate your hormone levels. Wearing panty liners can help prevent unexpected accidents and stained clothing.

Be sure to pay attention to your bleeding and other symptoms. Heavy bleeding isn’t a normal reaction to the pill. If it happens, you should make an appointment with your doctor.

Though spotting is a nuisance, birth control pills are a safe, effective form of contraception. If you find that birth control pills aren’t the right match for you, don’t fret. There are many different types of birth control options available today.

Your doctor can help you find the best fit for your body and your lifestyle.

Pro tip Wearing panty liners can help prevent unexpected accidents and stained clothing.