The downsides to The Pill: side-effects and complications

As outlined in the two previous blog posts in this series, there are many different contraceptive Pills on the market in Australia, and they have many benefits over and above contraception. Since its introduction over 50 years ago, one main advance has been a significant decrease in the dose of oestrogen in The Pill, which has helped to reduce oestrogen-related side-effects and complications. However, some women still experience side-effects when taking some Pills, and the Pill does slightly increase the absolute risk of very rare but serious complications.

When deciding whether or not The Pill is a good idea for you (and if so, which one), it’s important to weigh up the likely benefits (reliable contraception, lightening periods, helping with period pain, reducing ovarian cancer risk etc) with the possible side-effects and very small risk of serious complications. Have a chat with your doctor to discuss these issues in more detail…

Are there any medical conditions where it’s not safe to take the combined Pill?

There are some medical conditions in which it’s not safe to take the combined (oestrogen plus progestin) contraceptive pill – largely because of the oestrogen component. For example:
– Migraines with visual aura
– Being ≥ 35yo and a smoker
– Poorly-controlled high blood pressure
– Breast cancer
– Having had a stroke, heart attack, or a venous thromboembolism (blood clot in the leg and / or lungs)

If you have any of the above conditions I’d strongly recommend that you consider a progestin-only contraception (such as: a progesterone-only Pill; Mirena intrauterine device; or Implanon arm implant), or a non-hormonal option (such as the Copper intrauterine device). Talk about your options with your GP or gynaecologist.

Acknowledged side-effects of The Pill

There are several known side-effects of the combined (oestrogen plus progestin) Pill that have been validated by research. These include nausea, breast tenderness, and decreased libido, which are experienced by < 10% of women. There are several things you can try to help with these side-effects, as outlined below.


Approximately 5% of women experience nausea when they start taking the combined Pill. If this is the case, it would be worth doing a pregnancy test, to make sure that you’re not actually pregnant! If this is normal, consider persisting for three months on the same Pill: your nausea is likely to settle down with time.

If the nausea doesn’t settle after three months, it would be worth considering:

– Reducing the oestrogen dose: if the pill you’re currently taking has ethinyloestradiol as its oestrogen ingredient, consider changing to a pill formulation with a lower dose of ethinyloestradiol (eg. from a pill that contains 50 micrograms of ethinyloestradiol to one that only contains 35 micrograms, or from 35 to 30 micrograms, or from 30 to 20 micrograms).

– Taking your Pill at night, instead of in the morning. This means that you’ll be asleep (instead of awake) when the hormone levels in your bloodstream are at their highest.

– Changing to a progesterone-only form of contraception, such as a progesterone-only Pill, Mirena intrauterine device, or Implanon arm implant

Breast tenderness

Breast tenderness is a relatively common side-effect of the combined pill. The oestrogen ingredient in The Pill may cause ‘hypertrophy’ (or swelling) of fatty breast tissue, which some women find uncomfortable. Pill-related breast tenderness usually resolves after the three months, so consider persisting with your current pill formulation if you can bear it.

If your breast tenderness doesn’t settle after three months, management options include:

– Reducing the oestrogen dose: if the pill you’re currently taking has ethinyloestradiol as its oestrogen ingredient, consider changing to a pill formulation with a lower dose of ethinyloestradiol (eg. from a pill that contains 50 micrograms of ethinyloestradiol to one that only contains 35 micrograms, or from 35 to 30 micrograms, or from 30 to 20 micrograms).

– Reducing the progesterone dose: eg. from 150 micrograms of levonorgestrel to 125, or 125 micrograms to 100.

– Changing to a different type of progestin, such as drosperinone

Decreased libido

There is mixed evidence about whether or not the combined Pill can lead to reduced libido. As we all know, women’s sexuality and libido is very complex: some researchers think that it may be coincidence, that women start taking the contraceptive pill as the thrill of a new relationship wears off, and libido and the frequency with which a couple has sex naturally slows down a little. One systematic review (a type of research that amalgamates several other research papers about a topic) found that the majority of women do not experience any change in libido or sexual desire after starting the combined Pill. 22% of women actually reported an increase in sexual desire, and 15% a decrease.

Unfortunately there are no easy options to increase your libido, if you feel like it has dropped off since starting The Pill. You could consider trying a non-hormonal form of contraception, such as the Copper intrauterine device. Perhaps a glass of wine, a massage, and your partner doing all the housework and childcare for the day would also be worth a try: it certainly wouldn’t hurt!

Breakthrough bleeding

Breakthrough bleeding is unpredictable bleeding or spotting, that occurs outside the time you’re expecting a period (or ‘progesterone-withdrawal bleed’). This can occur: during the three weeks of hormonal pills (if taking a pill that has 21 hormonal tablets and 7 ‘sugar’ tablets); or when trying to ‘tricycle’ your Pill (ie. take back-to-back weeks of hormonal tablets, for up to three months at a time).

Breakthrough bleeding occurs in about half of women during the first month they take the combined Pill: more often than not, it quickly improves over subsequent months. Breakthrough bleeding is due to the hormonal ingredients in the combined Pill. At a basic level, oestrogen thickens and builds up the thickness of the lining of the uterus, while the progestin ingredient maintains the stability of the lining. If the oestrogen dose in your pill is too low, the uterine lining may be frail and will shed easily; if the progestin dose is too low, the uterine lining will be unstable, and will also shed too easily. Both scenarios can lead to breakthrough bleeding. One common cause of breakthrough bleeding is accidentally forgetting to take a pill.

Like many side-effects of the combined Pill, breakthrough bleeding tends to improve within three months of use. If you are experiencing ongoing breakthrough bleeding, have a chat with your GP. They may consider:

– Investigations to rule out other causes of irregular bleeding (eg. a transvaginal ultrasound to see if you have a polyp in the uterine lining / cervix; testing for sexually transmitted infections; completing a cervical screening test)

– Changing to a Pill that has a slightly higher oestrogen dose (eg. 30microgram of ethinyloestradiol, rather than 20 micrograms)

– Changing to a Pill that contains a ‘third generation’ progestin, such as gestodene or desogestrel

– Changing from a Pill with a 24 / 4 pattern (ie. 24 days of hormonal tablets, followed by 4 days of ‘sugar’ tablets) to one that has a 21 / 7 pattern (ie. 21 days of hormonal tablets, followed by 7 days of ‘sugar’ tablets)

– Changing to a different form of contraception, such as a ‘Nuvaring’

Perceived side-effects of The Pill

In contrast to the recognised side-effects outlined above (which are supported by research), there are also some side-effects which are often reported by women, but not necessarily supported by research studies. These include: weight gain, bloating and fluid retention, headaches, and impacts on mood and mental health.

Weight gain, bloating, fluid retention

A meta-analysis (the highest level of research, in which the results of lots of high level research studies are collated into one overarching conclusion) in 2014 found no significant association between taking the combined Pill and gaining weight. Unfortunately, we all tend to gain weight as we age, whether or not we take The Pill. However, from a pharmacological perspective, there is a mechanism by which The Pill may cause excess fluid retention, bloating (and perhaps cyclical weight gain): excess oestrogen is thought to lead to water retention and bloating, which could theoretically lead to cyclic weight gain. In addition, oestrogen may cause hypertrophy (or swelling) of fatty tissue, so women may notice an increase in breast or hip size while on The Pill.

If you are concerned about possible weight gain while on the Pill, it would be prudent to take a lower-dose product, with a lower oestrogen and progesterone done. A Pill that contains drosperinone as its progestin ingredient would also be a good idea: drosperinone has a mild diuretic effect, so may help with fluid retention and weight gain.


There is conflicting data about whether or not the combined Pill leads to worse headaches. Some research trials show that women on higher oestrogen dose pills (eg. containing 50 micrograms of ethinyloestradiol) are more likely to have headaches than those on lower oestrogen dose pills. Headaches tend to occur when the hormonal pills are stopped (and the ‘sugar’ pills taken), so they may be due to oestrogen withdrawal. Hence, options to manage troublesome headaches include:

– Taking your Pill back-to-back, with up to three months of continuous hormone pills between weeks of ‘sugar’ pills

– Changing to a lower oestrogen dose Pill (eg. 20 or 30 micrograms of ethinyloestradiol, rather than 35 or 50 micrograms)

– Changing to a pill that has oestradiol valerate as its oestrogen ingredient (eg. ‘Qlaira’ brand)

– Ask your GP if you can use an oestradiol patch during the week of ‘sugar’ pills

Interestingly, the prevalence of headaches amongst women who use The Pill tends to decrease with each subsequent month. So it might be worth persisting for at least three months, to see if your headaches get better over time.

Impact on mood and mental health

There is conflicting research as to whether the combined Pill can lead to new, or worsen pre-existing, depression or mental ill health. Some studies have shown an increased rate of depression in women who take the combined pill; other show little or no effect. Most studies suggest that the combined Pill does not negatively impact mood for most women. Monophasic pills (where every hormonal tablet is the same) lead to less mood ups and downs than multi-phasic options (where there are two, or three different hormone tablets that are taking during the weeks of hormonal tablets). Women who have previously had depression are more likely to be troubled by a recurrence or worsening of their depression if they are on The Pill.

If you feel like your mood or depression is worse when on The Pill, see your GP who may:

– Formally evaluate you for depression

– Change to a lower oestrogen dose Pill (eg. 30 micrograms of ethinyloestradiol, rather than 50 or 35 micrograms)

– If you are taking a multiphasic Pill: changing to a monophasic option instead

– Trying a combined Pill that has oestradiol as its oestrogen ingredient (eg. ‘Zoely’ brand)

– Suggest taking your pill back-to-back, with up to three months of continuous hormonal tablets between weeks of ‘sugar’ pills

– Suggest an alternative contraception, such as the Copper IUD

Managing side-effects of The Pill

If you are experiencing annoying side-effects from The Pill, have a chat with the doctor who prescribed The Pill originally. Many side-effects get better over time, so your doctor may suggest persisting with that particular pill brand for at least three months. Another reason to persist for at least three months, is if you swap to a different pill after only a few weeks, and keep doing so every time you experience a side-effect, you may quickly run out of Pills to try! So, if it’s safe to do so, consider staying on the same Pill for at least three months, before changing to another brand. If, at the three month mark, you are still troubled by the same side-effect, your GP may suggest changing to a slightly different Pill, as outlined above.

Rare but serious complications due to The Pill

There is a very small increased risk of serious complications due to the combined Pill: namely, a blood clot forming in the leg(s) and / or lung(s); and a slightly increased risk of breast cancer. While reading these sections below, it’s important to keep in mind that in most cases, an unintended pregnancy is much more dangerous than taking The Pill. For example: the risk of a venous thromboembolic event (blood clot forming in the leg and / or lung) is much much higher during (and immediately after) pregnancy, than it is when taking the combined Pill.

Venous thromboembolic event (VTE)

The baseline risk of a woman who is not taking the combined Pill, of having a VTE (blood clot in the leg and / or lung) is approximately 3 per 10,000 woman years. If on the combined Pill, this increases three-fold, to approximately 6 per 10,000 woman years. However, during pregnancy, this risk jumps significantly to 20 per 10,000 woman years, then jumps even higher to 50 per 10,000 women years during the six weeks after pregnancy. So remaining on the combined Pill, and thus avoiding an unplanned pregnancy, is likely to be much safer than coming off it, then having an unintended pregnancy (for many reasons!)

In terms of the different combined Pills on the market, those with the lowest VTE risk contain low oestrogen doses (eg. only 20 or 30 micrograms of ethinyloestradiol, compared to 50 micrograms), and levonorgestrel as its progestin ingredient (rather than desogestrel, gestodene, cyproterone or drosperinone). For example, a Pill with 30 micrograms ethinyloestradiol and a third generation progestin (such as gestodene, desogestrel) or drosperinone has a VTE risk 60 – 70% higher than a pill that contains 30 micrograms of ethinyloestradiol and levonorgestrel.

If you have a history of a blood clot in your leg or lung, you should not take the combined Pill in future: progesterone-only or non-hormonal contraceptive methods are safer. If you have other risk factors for VTE (such as age > 35 yo, obesity, a known thrombogenic mutation, and / or smoking), you’ll need to have a nuanced discussion with your GP about the potential benefits and risks of the combined Pill, compared to other forms of contraception.

Strokes and heart attacks

While the combined Pill is associated with an increased risk of heart attacks and ischaemic stroke, the absolute increase in risk is extremely small: approximately 10 additional heart attacks or strokes per 1,000,000 women. Put another way, it is estimated that among 10,000 women on the combined Pill, the use of the combined Pill for one year would result in:

– two additional strokes

– one additional heart attack

If you have additional risk factors for stroke or heart attack (such as obesity, smoking, migraine with aura, uncontrolled high blood pressure or poorly-controlled diabetes), your GP will probably suggest that you use a progesterone-only or non-hormonal form of contraception.

Breast cancer

Combined Pills are associated with little to no increased risk of breast cancer. Any effect appears to be temporary, and limited to current or recent (within five years) use of the combined Pill.
Women who have previously had breast cancer are advised not to take the combined Pill in future, as there is a theoretical risk that taking hormonal pills may stimulate any remaining breast cancer cells to become more active. Having a BRCA gene mutation is not a reason not to take the combined Pill.
Some studies suggest that women on the combined Pill have lower risks of some benign (non-cancerous) breast conditions, such as fibrocystic changes and fibroadenomas.


As outlined in previous blog posts in this series, there are several strong benefits to taking the combined Pill, including: avoidance of an unplanned pregnancy; helping with heavy and painful periods; reducing the risk of ovarian and uterine cancer; reducing the formation of ovarian cysts; and helping to manage acne and excess hair.
The combined Pill is known to have some side-effects, all of which tend to improve if you persist through them for three months or so. These side-effects include: nausea; breast tenderness; decreased libido; and breakthrough (unpredictable) bleeding. There is no strong evidence that the combined Pill causes weight gain.
There is a slightly increased risk of blood clot(s) forming in the leg(s) and / or lung(s), which is a recognised but rare complication of the combined Pill.
Watch out for the next blog post in this series, which will cover frequently asked questions about The Pill!

We look forward to collaborating with you to help you to be your best.