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Bleeding on the Contraceptive Pill: What Causes It?

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causes for bleeding on the contraceptive pill UCI UC Irvine/Flickr

Normally, when a woman takes the contraceptive pill she has a week off where she either doesn’t take anything or takes "dummy" pills that are inactive. During this time she will have her normal period. After these seven days, she resumes taking the pill.

Sometimes, bleeding may occur at other times during the cycle while she is taking the pill. This is called "breakthrough bleeding".

What Causes Breakthrough Bleeding?

There are several reasons for spotting while on birth control:

• If you have just started taking the pill you may bleed between periods because of the hormone disruption and your body getting used to the pill. It should stop after a few months and is not dangerous. It is usually milder than a regular period so you may need to wear pantyliners. If bleeding lasts longer than three months or is heavy, you may need to try a different pill or type of contraception.

• If you forget to take pills, you are more likely to have irregular bleeding.

• If you smoke, you are more likely to have breakthrough bleeding because cigarettes have an anti-estrogenic effect that can disrupt cycles.

• Combined oral contraceptives that contain smaller amounts of active ingredients may cause irregular bleeding patterns more than pills with higher doses.

• Older generation pills don’t control bleeding as well as some of the newer pills.

There are other causes of breakthrough bleeding which may not be related to the pill itself. These are:

• Medication use. Some medications interact with the pill. Check with your doctor that your medication is compatible with your contraception.

• Sexually transmitted infections. These may cause bleeding in between periods. The pill does not protect against sexually transmitted infections.

• Other gynecological illnesses or cancer may cause bleeding. If the cause is known not to be due to the pill, the doctor may ask if he can do a Pap test to check for abnormal changes to the cervix or cervical cancer.

• It is still possible to get pregnant while on the pill, especially if certain antibiotics have been used or the woman has been unable to take her pills due to vomiting (this reduces the amount of pill in her blood which reduces the effectiveness of the contraception).

• Spotting can occur in pregnancy due to implantation and the cervix is more prone to bleeding during this time, so the doctor may test your blood or urine for HCG to confirm or disprove pregnancy.

How to Reduce Breakthrough Bleeding

If you have only recently started taking the pill, you may find the problem settles on its own. You can also try a combined pill with a higher amount of active ingredient or try a different contraceptive device altogether.

Try to remember to take your pills on schedule. Do it at the same time each day and set an alarm so you don’t forget.

This is why some packs of pills contain dummy pills, so you don’t get out of the habit of taking them. If you keep forgetting, an alternate contraceptive may be better for you.


The pill is associated with an increased risk of blood clots. If you have any symptoms such as severe headaches, chest pain, vision or speech problems, coughing up blood, numbness or weakness in limbs, breathing difficulties or collapse, you or a relative must call an ambulance. These are signs of a blood clot which can be fatal without treatment.

Women should not have the pill or any contraceptive containing the same hormones as the pill if they have ever had breast cancer.This is hormone-dependent and may recur or get worse as a result of the pill. Women with other pre-existing illnesses who are taking medications may not be considered suitable candidates for the pill.

Women Who Should Not Take the Pill

Anyone over 50 years or overweight (BMI over 39kg/m), even if you are healthy.

Anyone with a family history of blood clots under the age of 45.

Anyone with superficial thrombophlebitis (red and sore veins on the surface of your legs)

Anyone with circulation problems (not an absolute contraindication, but you may be advised not to).

Anyone with disabilities that cause mobility problems, including wheelchair users.

Anyone who has had diabetes more than 20 years.

Anyone with uncontrolled high blood pressure.

Anyone who smokes more than 40 cigarettes a day.

If you are breastfeeding, the pill can reduce your milk so you should NOT use it.

Choose different contraception, such as a condom.

If you have migraines you should not take the pill, particularly if they are with aura and you are over 35 years old.


Combined Oral Contraceptive Pill, Patient UK. Web. 17 May 2012. http://www.patient.co.uk/health/Combined-Oral-Contraceptive-Pill.htm

Breakthrough Bleeding with Combined Hormonal Contraception, Patient UK. Web. 17 May 2012.

Reviewed May 18, 2012
by Michele Blacksberg RN
Edited by Jody Smith

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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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