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Birth control pills are one of the most commonly used forms of contraceptives to prevent unwanted pregnancies. They are largely safe and effective.
However, your body may take some time getting used to them. This is because oral contraceptives generally contain synthetic hormones that interfere with the normal functioning of the body.
When you first start using this medication, your hormonal balance may get disrupted, triggering certain adverse side effects. But as you continue using it for a few weeks or months, the body will grow accustomed to it, your hormones will stabilize and the side effects will disappear on their own. The same happens when you go off the pill.
Side Effects of Birth Control Pills
Here are the common side effects associated with birth control pills.
1. Spotting between periods
Estrogen and progestin are female sex hormones that control the functioning of the uterus and ovaries. Birth control pills contain small amounts of synthetic estrogen and progestin that inhibit the activity of natural estrogen and progestin found inside the female body.
The regular intake of this medication alters the working of the reproductive system in different ways to prevent pregnancy. It is known to trigger hormonal fluctuations that cause thinning of the endometrium, or the inner lining of the uterus, especially during the first three months of taking the pill.
Your endometrium needs to be thick for the fertilized egg to properly attach to it and result in a successful pregnancy, but birth control pills keep that from happening.
The body normally sheds the endometrium at the end of the monthly menstrual cycle when the egg doesn’t get fertilized by a sperm. The disintegrated uterine lining is eliminated from the body in the form of menstrual bleeding.
However, oral contraceptives cause part of the uterine lining to break down in the middle of the menstrual cycle, causing mild bleeding or spotting between periods. Nearly half of all those on the pill experience this kind of spotting or untimely bleeding, but it tends to go away after the third month of use as your body becomes adjusted to the new hormones by then. (1)
Cortisol is a steroid hormone secreted by the adrenal glands and is involved in many body functions. It is mainly responsible for controlling how your body responds to stress. This is why it is often referred to as the “stress hormone.”
Oral contraceptive pills are known to increase the level of cortisol in the body, which can make you more sensitive to stress and thereby trigger headaches. Moreover, birth control pills may trigger inflammation in the body, which can also contribute to headaches.
According to a 2005 study published in the American Journal of Obstetrics and Gynecology, about 10% of users experience frequent headaches during the first month of taking the pill. (2)
Fortunately enough, this problem is usually a temporary grievance as the headaches subside once the body gets accustomed to the new oral contraceptive.
3. Changes in vaginal lubrication
The chemical estrogen present in birth control pills binds the natural estrogen circulating in the blood to make it unavailable for use. This helps maintain a steady amount of estrogen inside the body.
Conversely, pills with a high amount of estrogen tend to increase estrogen in the body, which may result in increased vaginal discharge. (5)
Starting a new birth control pill causes fluctuations in the levels of your sex hormones, which can lead to water retention and bloating, especially in the breast and hip areas. (6) Irritable bowel syndrome and other gastrointestinal tract disorders can further exacerbate this side effect.
Many people mistakenly assume this bloating to be actual weight gain, but you will shrink back to your normal size once you discontinue the pill or your body gets acclimated to it. The estrogen in these pills can even make your fat cells swell up but won’t increase their number.
The American Journal of Obstetrics and Gynecology suggests that the condition will most likely improve on its own, possibly within six months of starting the medication.
5. Low thyroid and testosterone levels
The use of oral contraceptives increases levels of sex hormone-binding globulins (SHBG) and thyroxine-binding globulins. These proteins trap testosterone and thyroxine hormones to put them out of circulation. (7)
Both these hormones are involved in key bodily functions, and so their unavailability is bound to trigger some adverse outcomes.
Low thyroxine levels slow down metabolism, which makes you susceptible to weight gain. Plus, it can trigger depression, constipation, skin dryness, memory loss, cognitive decline, and hair fall, among many other symptoms. Women who do not have enough thyroid hormone run a higher risk of infertility and miscarriage.
Lack of testosterone, on the other hand, can make you lose muscle mass and sex drive.
Going off the pill may not bring down the elevated levels of these proteins, which can cause chronic hormonal problems, such as estrogen dominance.
Some people experience mild nausea when they start a new oral contraceptive, but it goes away after some time as their body gets acclimated to the medication. (8)
You can reduce the risk of this side effect by taking the pill with food or at bedtime. Medical attention is needed if nausea persists for a long time or becomes too severe.
7. Breast tenderness
You may experience swelling or tenderness in the breasts during the first few weeks of taking a new oral contraceptive pill. (9) Limiting your caffeine and sodium intake as well as wearing a supportive bra may help ease the discomfort to some degree.
This side effect usually resolves on its own as your body gets used to the medication, but seek medical help if:
- You notice a lump in the breast.
- You develop severe breast pain.
- The pain and tenderness last for more than a few weeks.
8. Breast cancer
Oral contraceptive use increases the risk of breast cancer slightly (by about 5 more cases per 100,000 women). Risk increases primarily during the years of contraceptive use and tapers off during the 10 years after stopping.
The use of oral contraceptives in patients was indicated to increase the risk of breast cancer. The longer the duration of using oral contraceptives, the higher the risk of breast cancer.
Risk is highest in women who began to use contraceptives before age of 20 (although absolute risk is still very low). (10)
9. Mood changes
According to a 2015 study published in Human Mapping, the use of oral contraceptives may cause cortical thinning in certain areas of the brain that can affect mood and behavior. (11)
However, these findings were based on a sample size of only 90 women and need to be corroborated with more large-scale human trials.
10. Yeast infection
Oral contraceptives disrupt the balance of estrogen and progesterone in the body, which can increase the risk of vaginal yeast infections. This is particularly true for pills that contain high amounts of estrogen, which is a known contributor to yeast infections.
In fact, a 2006 study conducted by the University of Michigan School of Public Health found that women on birth control pills are two times more likely to develop yeast infections than those who don’t. (12)
Poorly managed diabetes, high sugar intake, too much alcohol, and low immunity can further increase this risk.
11. Blood clots
Birth control pills have been associated with an increased risk of blood clots, especially if you are using combined oral contraceptives. Blood clots are one of the more dangerous side effects of this medication but are thankfully quite rare. (13)
Nevertheless, it is important you consult your gynecologist before trying any new birth control pill to learn about its potential side effects.
Also, you must seek immediate medical help if you experience respiratory distress, pain in the chest, or swelling in the legs after starting the pill as these could indicate a clot in the heart or lungs.
12. Decreased libido
Birth control pills introduce synthetic estrogen and progestin into the body while simultaneously halting the production of testosterone. These hormonal changes can adversely affect your sex life by lowering your libido (sex drive), decreasing your ability to have orgasms, and increasing pain during intercourse. (14)(15)
In most cases, these side effects will subside after 3–4 years of taking the pill, but seek medical help if they persist beyond that.
When to See a Doctor
Consult your gynecologist if you already have the following complications:
- Blood clots in the veins
- Hypertension or other cardiovascular disorders
- Stroke in the past
- Breast cancer
Note: Lastly, remember that these pills do not protect you against sexually transmitted infections.
Like any other medication, birth control pills also come with certain side effects. Different people may respond differently to the same birth control pill as humans are built differently and undergo various bodily changes over time.
Thankfully, most of the side effects associated with oral contraceptives are non-threatening and temporary. You can easily manage them at home with some self-care measures.
However, consult a doctor if the problem becomes too distressing or persistent. You may have to discontinue the pill altogether in the case of serious side effects such as blood clots or hypertension, and the doctor will recommend a safer alternative.
Birth control pills are medicine – use them only after consulting your gynecologist in the hospital or online. Moreover, taking birth control pills is not a good idea if you smoke, are 35 or older, or are obese.