Some people may experience a change in breast size as a temporary side effect when taking birth control pills. It can take several months for breasts to return to their regular size.

Although birth control pills can affect your breast size, they don’t change breast size permanently.

Birth control pills are the most common form of hormonal contraception used in the United States today. They work to prevent unplanned pregnancy in three ways:

  • preventing ovulation
  • increasing and thickening cervical mucus
  • thinning the uterine lining

Before you begin using hormonal birth control, it’s important to understand how it can affect your body and what side effects you may experience.

Birth control pills contain the synthetic hormones estrogen and progestin, which also naturally occur in your body.

When you begin taking birth control, your levels of these hormones rise.

At these increased levels, these hormones can generate changes in your body, such as a temporary increase in breast size or weight gain.

The hormones in birth control pills may cause temporary changes in your breasts when you first begin using birth control pills. In most cases, any change in breast size is the result of fluid retention or temporary weight gain caused by the increase in hormones.

These temporary changes typically subside within 2 to 3 months.

In addition to changes in breast size, the hormones present in the pill can cause other side effects.

These can include:

  • changes in menstrual cycle, such as heavy bleeding
  • mood changes
  • headaches
  • nausea
  • weight gain
  • breast tenderness

Some people may also experience more severe side effects from birth control pills.

These rare side effects can include:

  • high blood pressure
  • blood clots
  • heart attack
  • stroke

Birth control pills that contain estrogen are more likely to cause these severe side effects.

These side effects are less likely with progestin-only pills. This comes at a trade-off, though. Progestin-only pills are less effective at preventing pregnancy than those containing estrogen.

Birth control pills are generally safe to use. However, some people are advised not to take birth control or to take it with the understanding they may be at higher risk for more severe side effects.

People who should use additional caution when taking birth control include those who:

  • smoke and are over age 35
  • have a history of high blood pressure
  • have unhealthy levels of cholesterol
  • have been diagnosed with clotting disorders
  • have a history of migraine with aura
  • are overweight or obese and have additional medical issues

Before starting hormonal birth control, it’s important to speak with a doctor about any possible side effects or complications.

Some people may not experience a change in breast size when taking birth control. If you’re looking to increase the size of your breasts permanently, you can discuss your options for breast augmentation with a doctor.

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The hormones in birth control pills may cause a temporary increase in the size of your breasts when you first begin using birth control pills. In most cases, any change in breast size is the result of fluid retention or weight gain caused by the increase in hormones.

These temporary changes typically subside within 2 to 3 months.