Birth Control Pills: The 5 Most Common Side Effects

Despite their age, birth control pills are still one of the most used methods of preventing conception. Short-term side effects are typically very mild and go away on their own within a few weeks.
Birth Control Pills: The 5 Most Common Side Effects

Last update: 30 May, 2021

One of the most widely used female contraceptive methods around the world are birth control pills. Accessible, inexpensive and easy to manage, and yet they can cause unwanted effects.

Birth control pills were formulated over 50 years ago. They work by varying estrogen levels and preventing ovulation. Studies show that in addition to avoiding pregnancy, they also protect against conditions such as pelvic inflammatory disease (PID) and ectopic pregnancy.

The use of this contraceptive method is very simple, which makes it very popular among young women. It is enough to take one pill a day at the same time; treatment should begin on the first day of the menstrual cycle or the first Sunday thereafter.

Mechanism of action of the contraceptive pill

Birth control pills prevent ovulation
Estrogen suppresses the activity of follicle stimulating hormone (FSH) in the ovary, preventing the egg from developing.

Before talking about the side effects of oral contraceptives, it’s important to understand their mechanism of action. This is because most of the unwanted symptoms occur due to the hormonal changes induced by the pill.

Birth control pills modify the level of estrogen hormones, providing estrogen, ethinyl estradiol, and progestin. The most important components are estrogen and progestogen, which generate the changes needed to prevent ovulation.

Estrogen suppresses the activity of follicle-stimulating hormone (FSH) in the ovary, preventing the appearance of a dominant follicle, from which a mature egg will eventually develop. Estrogen also regulates and balances the menstrual cycle.

Progestogens, on the other hand, inhibit the secretion of luteinizing hormone (LH), which prevents the release of a mature egg. Both compounds work together to generate the contraceptive effect, as they wouldn’t achieve it separately.

The 5 most common side effects of birth control pills

Despite the great use of pills as contraceptive methods, the hormonal changes produced tend to generate side effects. They usually don’t have too much impact on quality of life and disappear on their own after a few days.

Up to 30.8% of women taking contraceptives experience at least one adverse reaction. The frequency of symptoms presented may vary according to age, race, health status (and studies consulted).

However, among the symptoms and signs that may appear more frequently as part of adverse effects, the following stand out:

1. Weight gain

The study just cited and published in the journal Pharmaceutical Care states that weight gain is the most common side effect of birth control pills. It can occur in up to 14% of women. In most cases, weight gain is due to fluid retention.

Weight changes are usually not that significant in women who didn’t suffer from obesity before starting the pill. In general, weight gain is estimated to be usually less than 2 kilograms, so it’s a minimal gain and shouldn’t be cause for concern.

This symptom is mostly temporary and disappears on its own after 2 to 3 months of continued use. However, there is no conclusive evidence confirming the relationship between weight gain and the use of birth control pills.

2. Headache

Headache is a common symptom during periods, and it’s also one of the side effects of the birth control pill. It can be physiologically explained by a sudden drop in estrogen levels in the body.

Women taking the pill have to manage estrogen levels up to 4 times higher than normal. This causes a sharp decline to occur during menstruation and the subsequent appearance of headaches.

This symptom doesn’t depend on the dose of hormones introduced through the pill; in fact, estrogen in low doses even prevents the appearance of migraines. The frequency of this side effect is high and can appear in up to 20% of women according to various studies.

3. Nausea and vomiting

Nausea is one of the side effects of the birth control pill
Gastrointestinal symptoms are a common effect of the pill.

The birth control pill can cause gastrointestinal symptoms, including nausea and vomiting. However, they are generally mild.

In most cases, no treatment is needed and they resolve on their own over time. In fact, studies show that they spontaneously regress in 35.5% of cases and only 4.5% require specialist medical treatment.

These symptoms are usually more intense when you start taking the pill; in this case, it may be useful to take it during meals or before going to bed. It’s important to keep in mind that if the nausea or vomiting doesn’t go away after three months, you should see your doctor.

4. Intermenstrual bleeding

This is a very common symptom: these losses can be confused with menstruation, but they occur before the expected date. They usually appear in the first three months of treatment or when you forget to take a pill.

Bleeding is considered an adaptive process of the uterus to a thinner endometrium. It can also be a consequence of estrogenic changes. Despite the bleeding, the pill is effective as long as all doses have been taken.

The duration of this symptom is usually less than 5 days and the losses are scarce. However, it is important to see your doctor if you experience heavy bleeding for 3 days or minor bleeding that exceeds 5 days.

5. Breast pain

Breast pain is very common when taking combined contraceptives, i.e. those based on estrogen and progestin. It isn’t known exactly whether the pain is caused by an increase in breast size or by stimulation of the pain receptors located in the area.

Breast pain typically subsides gradually, and should be unnoticeable after a few months. If the pain is constant and you feel a lump in your breast, you should consult your doctor immediately, or the specialist if the pain is very intense.

Other effects of contraceptives

These side effects appear acutely, however, taking the birth control pill for a long time can have health consequences. According to data provided by the National Cancer Institute, they increase the risk of breast and uterus cancer.

However, not all effects are negative, the same research institute states that oral contraceptives are able to reduce the risk of endometrial, ovarian and colon cancer.

Despite how long they’ve been around, birth control pills are still one of the most used popular methods of preventing conception. Short-term side effects are typically very mild and go away on their own within a few weeks.

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