Understanding Health Risks; Oral Contraceptive Pill

Most activities are associated with some form of health risk, such as driving a car, walking across a busy street or even just leaving a child unattended for a few minutes. Likewise inactivity (i.e. sedentary lifestyle ) can all have devastating consequences but to out right absolutely try to ban such activities is far from pragmatic and  in some instances  ludicrous.  One must also recognise that a particular activity might be beneficial in one aspect of health and harmful in another aspect of health.  It requires weighing up the benefit and harm form such activity before one can determine whether such an activity should be undertaken. The same is the case for all medical treatments be that in the emergency setting of a heart-attack, or managing a relatively minor ailment such as  viral respiratory infection or managing  chronic diseases such as asthma, diabetes or depression.

Recently I was informed of one of the critics of modern medicine discussing the risks associated with contraceptive pills and clearly the underlying problem is that this individual has not understood a number of concepts and from among them is the benefit and harms of such medicines thereby being able to weigh these in the context of the health status of a particular patient.



Side-effects (also known as adverse effects) are defined as unwanted effects of a treatment which can at times be a transient nuisance or at times harmful leading to injury of the body.  Most common side-effects are headache, rashes and gastrointestinal upset and nearly all medicines are prone to this in one person or another, however a many multitude more patients will be fine without any side-effects whatsoever. Often medicines will have several active (or pharmacological) properties thus allowing a single medicine to be used for several different illnesses and it is commonly the presence of these other active properties that result in side-effects.  Whenever we are presented with side-effects one always needs to compare them to the benefits of the medication.


Prophetic Medicine

Side-effects are seen with many Prophetic medicines  and so it is natural to find it with other medicines. Examples of such side effects are headaches or faintness  with blood cupping, abdominal bloating  with senna, diarrhoea with honey, fatty milk residue inside the mouth which can cause harm, black chradh (Silqh) causing constipation, flatulence and harming the blood, etc . There are many more but the point is because these medicines have several properties where one property can be beneficial in one illness the other properties can cause side-effects.   There will be ways to try and neutralise these side-effects by mixing with other substances and this is no different from modern medicine.


Combined Oral Contraceptive Pill – COCP

Blood Clots – Venous thrombo-embolism, VTE

Combined oral contraceptive pill (COCP) contains both oestrogen and progestogen and is usually taken for 21 days and then given a week break. They have an increased risk of blood clots which does not occur with the progestogen only pill (POP- also called mini pill).  The blood clots that we are discussing are those that occur in the deep veins (DVT) of the legs these can then break off and end up in the lungs (pulmonary embolism, PE) with the latter being life threatening. There are many causes of VTE such as hip fractures, immobility, long distance flights, cancers, etc and for our discussion COCP usuage.

The risk of VTE in women of reproductive age is approximately 4–5 per 10 000 woman-years in those who do not use oral contraceptives. A woman-year is a unit measure of  one year as a woman while in reproductive age, under 45 years of age, it is used as a means to standardise the time duration the COCP is used. The risk of VTE amongst COCP users is approximately  9–10 per 10 000 woman-years.  The risk returns to that of non-users within weeks of discontinuation.

Whilst COCP does increase a woman’s VTE risk, to double from a relative perspective however in absolute terms it is still very small. This can be appreciated if we compare it to the risk of VTE associated with pregnancy which are much higher at 29 per 10,000 woman-years being at least 7 times greater relatively. In the immediate postpartum (after delivery)  period VTE risk is 300–400 per 10,000 woman-years being 80 times greater. This is what needs to be considered in trying to understand such risks.  Many human activities are associated with risk to health but one needs to look at the overall benefit and harms and put it in the correct context.  For comparison, results from a population-based case-control study involving people with a history of blood clots (VTE) found the relative risk of VTE to double after a long-haul journey (greater than 4 hours), regardless of the mode of transport. In a different (retrospective cohort) study of healthy individuals, the relative risk was increased four-fold for flights over 4 hours but the absolute risk remains extremely low — calculated to be 1 event per 4,600 long-haul flights. Based on this I don’t think anyone would advocate in a healthy individual against travelling for more than 4 hours as the risk of a blood clot can double or even quadruple. However we may advocate stopping the COCP for the travel or try to stretch you legs and walk every hour or so in higher risk individuals. (Other measures such as class 2 stockings can help too).



COCP increases the risk of strokes in women under 45 yrs of age  from 1 in 10,000 women  to 1.5 – 2 in 10,000 women. However it is  predominantly in those who suffer from migraine with aura or with high blood pressure, hence COCP is not used in such women. Not all headaches are migraines and not all migraines have aura. Aura are disturbances in the senses most often in the form of flashing lights or tunnel vision or an odd smell prior to the headache. If migraines with aura develop while on the COCP then this shows that the person has a propensity to develop migraine and the COCP needs to be stopped because of the risk of stroke.

Migraine with aura itself is associated with stroke and heart attacks  even without COCP usuage, particularly in cigarette smokers, those with high blood pressure or obese women. These three confounding risk factors are far more strongly linked with stroke with much higher risks than the COCP.  The mini-pill (POP) is not linked to migraine, strokes or heart attacks and so can be used in such women.


Heart Attacks

Heart attacks are associated with a very small increase risk with COCP, the exact amount differs between studies and some studies have failed to show an increase. This is because the underlying risk of heart attacks in women under 45 years is about 0.5  in 10,000 (same as 1 in 20.000) being rare and the relative increase is small thus making the absolute risk close to negligible. For comparison, pregnancy and delivery carries a higher risk of a heart attack estimated at about 1 in 16,000 deliveries.



Quantifying background risk for daily activities is difficult as many illnesses have several different causal factors.  In the context of combined oral contraceptive pill ( COCP ) studies suggest that it is linked with an increase in cancer  of cervix and breast however at the same time it protects and reduces cancer of the ovaries and uterus (womb).  One cannot just take this statement and give that as the total picture because of the other factors at play. Firstly cervical cancer is associated with a viral infection called Human papillary virus (HPV)  which is transmitted sexually, predominantly seen amongst women who have had multiple partners and such women tend to take the COCP. Here the HPV  and multiple partners are  called confounding factors as they themselves are associated with increase risk of cancer of the cervix. In breast cancer there are a number of protective factors that reduce the risk of breast cancer such as having several pregnancies and more importantly breast-feeding duration. Again women who tend to use COCP for very prolonged periods will have few pregnancies and almost certainly never breastfeed for a significant duration. Cancer of the colon is also reduced in COCP users compared to non users .

Data from a large cohort study demonstrated that ever-use of oral contraceptives was associated with a 12% reduction in all-cause mortality (death) and no overall increased risk of cancer. Other studies have similarly shown no increased risk on mortality with use of oral contraceptives. However it does need to be pointed out that evidence from cohort and observational studies is less strong yet is the easiest methods used to calculate background risk where large populations need to be studied. Where as randomised controlled trials which are used for assessing treatment effectiveness are a stronger form of evidence.

The mini-pill (POP) is not associated with any cancer risk and one type of progestogen (megestrol) is used as a treatment for cancers of the breast, prostate and uterus (womb). POP is slightly less effective than the COCP for contraception (97% compared to 99%)  and comes with a different group of possible side effects namely irregular bleeding, fluid retention and weight gain.

Final Words

By now I hope that the reader is able to appreciate that a particular medicine might be beneficial in one aspect of health and harmful in another aspect of health. That health risks can sound alarming when looked at relative percentage increase but when assessed in detail through absolute risk it can be close to negligible. It requires weighing up the benefit and harms of such a medicine and then putting that into the context of the health status of an individual patient. COCP is not the right choice for everyone but is for many and as doctors we try to help patients make the right choices for themselves every working day. To make out-right blanket statements that such medicines are harmful for everyone just indicates the medical ignorance of the claimant. Listening to such claimants only confuses individuals and as such I advise that health contention needs to always be referred back to the experts in the field.



  • http://www.fsrh.org/pdfs/CEUGuidanceCombinedHormonalContraception.pdf
  • http://cks.nice.org.uk/contraception-combined-hormonal-methods#!scenarioclarification:5
  • http://cks.nice.org.uk/dvt-prevention-for-travellers#!supportingevidence1
  • http://www.medscape.com/viewarticle/439354
  • http://www.sciencedaily.com/releases/2012/03/120326113709.htm

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