How do birth control pills work?

This is an automatically translated article.

The article was professionally consulted by Specialist Doctor I Pham Thi Yen - Obstetrician - Obstetrics and Gynecology - Vinmec Hai Phong International General Hospital.
Birth control pills are an effective method of birth control to prevent an unwanted pregnancy. Learn the mechanism of action, the side effects that the drug brings, as well as the factors to help you make the right decision in choosing an effective birth control method for yourself.

1. Classification of birth control pills

1.1 Combination drugs

Combination pills are drugs that contain synthetic (man-made) forms of the hormones estrogen and progestin. Most of the pills in each cycle contain hormones or active pills. Some common combination drugs are:
Monophasic drugs: These are used in a one-month cycle and each active pill delivers a dose of the hormone. Take the inactive pill at the last week of your cycle to get your period. Multiphasic pills: These are used in one-month cycles and provide varying levels of hormones during the cycle. Take the inactive pill at the last week of your cycle to get your period. Long Cycle Pills: Pills are taken for 13 weeks/cycle, i.e. take the active pill for 12 weeks, and in the last week of the cycle take the inactive pill and get your period. So people using this medicine will have menstrual cycles 3 to 4 times a year.

1.2 Progestin-only pills

It is a progestin-only pill without estrogen. This medicine is also called a minipill. This is a good option for women who cannot use estrogen for health or other reasons. For this drug, all the pills in the cycle work. There are no inactive drugs.

2. Action of oral contraceptives

2.1. Combination drug

Combination pills work in two ways, stopping your body from ovulating. and thicken cervical mucus. This mucus is the fluid around the cervix that helps sperm travel to the uterus so it can fertilize an egg. Once the mucus is thick, it will prevent sperm from reaching the uterus.
Combination drugs come in different forms. These include monthly blister packs that come in 21-day, 24-day, or 28-day cycles. Long-term regimen can follow 91 days/cycle. The user takes one pill each day at the same time of day.

2.2 Progestin-only pills

This drug's mechanism of action works primarily by thickening the cervical mucus and thinning the endometrium. The endometrium is where the egg is implanted after fertilization. If this lining is thinner, it will be harder for the egg to implant, which will prevent the pregnancy from developing. Also, progestin-only pills can prevent ovulation. Progestin-only pills, only available in packs of 28, users take one pill at the same time each day.

3. The effectiveness of birth control pills

If used correctly, birth control pills are very effective at preventing pregnancy. According to the CDC (Centers for Disease Control), both combination pills and progestin-only pills have a 9 percent failure rate with typical use. This equates to a chance that for every 100 people using oral contraceptives, only 9 women will get pregnant.
To be fully effective, oral contraceptives should be taken at the same time each day. Some medicines can make either medicine less effective, such as: The antibiotic rifamycin; certain HIV medicines such as lopinavir and saquinavir; Certain anti-seizure medications such as carbamazepine and topiramate. The drug may also be less effective if the user has diarrhea or vomiting. In this case, the use of a backup method of contraception should be used to avoid unwanted pregnancy.

4. Side effects of birth control pills

Although birth control pills are safe for most women, they also have some side effects and risks. Every woman reacts differently to the hormones in the birth control pill. Some women, when taking birth control pills, will experience symptoms such as:
Decreased sex drive Nausea bleeding between periods Weight gain Painful or swollen breasts Mood changes These side effects, they can will improve after a few months of using the drug. If there is no improvement, doctors may recommend switching to a different type of birth control pill. If you experience any of the following, contact your doctor immediately. If you can't get to your doctor, go to the emergency room or urgent care center for an evaluation, as these symptoms are signs of some serious disorder, such as liver disease, gallbladder disease, stroke, blood clot, high blood pressure or heart disease.
Abdominal pain (stomach pain) Chest tightness Headache (severe) Eye problems (blurred vision) Swelling or pain in the legs and thighs

5. Frequently asked questions about birth control pills

5.1 How do I start birth control pills?

Ask your doctor when you should start taking birth control pills. If the day you started taking the pill is still in your period, you should still take it as directed. Your cycle will resume 25 days after starting the pack.
It is best to take the medicine at the same time every day. You can take it at any time of the day, but taking it before breakfast or at bedtime will make it easier to remember.

5.2 When should another pack of oral contraceptives be started?

You will start a new pack of birth control pills on the same day of the week that you start using it. If you are taking the 21-day pack, start the new pack seven days after you finish the old pack. If you are taking a 28-day pack, start a new pack after taking the last pill in the old pack. Start your new pack of pills on schedule regardless of whether you are menstruating or not

5.3 How do early birth control pills work?

Birth control pills are usually effective within the first month of use. To be on the safe side, some doctors recommend using another form of birth control, such as condoms, for the first month. After the first month, you can trust the pill's ability.

5.4 What if I forget to take my birth control pills?

If you forget to take your birth control pill, take it as soon as you remember. If you don't remember until the next day, go ahead and take two pills that day. If you forget to take your pill for two days, take two pills on the day you remember and two the next day. If you miss more than two pills, contact your doctor for specific instructions.
If you forget to take your pill, you must use another form of birth control. Because when you forget to take your pill, you increase your chances of releasing an egg from your ovary. If you forget to take one or more active pills then take a pregnancy test.

5.5 Can any woman take birth control pills?

Birth control pills can be used safely by most women. However, they are not recommended for women over the age of 35 who smoke. If you don't smoke, you can use hormonal birth control until menopause.
In addition, you should not use hormonal contraception if you have health problems such as: Blood clots in the arms, legs or lungs; Severe heart or liver disease ; Breast or uterine cancer; Uncontrolled high blood pressure; Migraine headache. In addition, you should notify your doctor if you have a first-degree relative (parent, brother, sister, brother) with a blood clot in your leg or lung.

5.6 What are the disadvantages of oral contraceptives?

Birth control pills do not protect against sexually transmitted infections. To make sure you're protected against infections, you'll need to use condoms in addition to your daily pill. If you forget to take your pill your risk of pregnancy increases.

5.7 What should be kept in mind when deciding which type of contraceptive to use?

Not every birth control pill is right for every woman. Talk to your doctor to choose which medication will work best for you. Factors to consider when choosing birth control methods include: Menstrual symptoms even if you are breastfeeding, Heart health status; Other chronic health conditions; Other medications you are taking.
Doctor Pham Thi Yen has 11 years of experience in examination and treatment in the field of Obstetrics and Gynecology. Doctor with strengths and deep understanding in:
Examination and consultation of normal pregnancies, pathological pregnancies, high-risk pregnancies Examination and treatment of gynecological diseases: cervicitis, cervical ectropion Surgery Laparoscopic surgery for gynecological diseases: ectopic pregnancy, uterine tumor, ovarian tumor Surgery for breast, vulvar, vaginal, cervical tumors Obstetric surgery: cesarean section, examination and treatment of endocrine disorders in women of all ages: puberty, reproductive age; perimenopausal age.

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.

Article reference source: webmd.com, healthline.com