There's a lot of noise surrounding the birth control pill, especially its side effects. But don’t let that put you off.
While side effects can happen, they’re usually mild, temporary, and settle down within a few months. Plus, everyone’s experience is different, too!
Whether you’re considering the combined pill or the mini pill, it’s helpful to know what to expect. In this guide, we’ll walk you through the most common birth control side effects, what’s normal, and when to seek advice.
Three key takeaways
Irregular bleeding (spotting), headaches, nausea, mood swings, bloating, sore breasts, and acne are some of the most common side effects of the contraceptive pill.
Most side effects of the pill are mild and temporary and should ease off within three months as your body adjusts to the new hormones.
Although the pill is well-tolerated by most people, it isn’t right for everyone. If your side effects haven’t subsided after three months, speak to your prescriber or GP. They may be able to recommend an alternative.
7 most common birth control pill side effects
1. Irregular bleeding
Irregular bleeding or spotting between periods is one of the most common side effects when starting the pill or switching to a new one. This happens because your body is getting used to the new hormones.
While it can be inconvenient, spotting is generally nothing to worry about and will settle down in a few months.
But if you're still getting irregular bleeding after three months, or it's heavy and bothering you, speak to your prescriber or GP. They can check if a different pill might suit you better or make sure nothing else is going on.
“Breakthrough bleeding can be more common with the mini pill because the progesterone thins your uterine lining, which can make it shed irregularly. The mini pill also doesn't contain oestrogen, which normally helps to keep the lining stable and prevents unexpected bleeding.
“Some people also choose to take the combined pill continuously without the usual pill-free break, but this can cause spotting due to the hormones thinning your uterine lining over time. This makes it more fragile and likely to shed small amounts of blood irregularly, particularly while your body is getting used to the hormones.
“If you're considering taking the combined pill continuously, this should always be done under medical supervision to ensure it's safe and suitable for you.”
While headaches and migraines can sometimes be a side effect of the pill – particularly when starting or switching methods – it can also be used to manage them if they're hormone-related.
The pill can help with headaches by stabilising your hormone levels and reducing fluctuations. However, if you take the combined pill with a pill-free break, the drop in oestrogen during that week can sometimes trigger migraines.
The mini pill is taken continuously without breaks, which prevents these hormone fluctuations and may reduce headaches or migraines.
It's important to note that if you suffer from migraines with aura, the combined pill may not be suitable for you as it can increase the risk of stroke. If this applies to you, speak to your prescriber or GP for advice.
If you’re feeling queasy after starting the pill, you’re not alone. The upside is that feelings of nausea are usually mild (meaning they don’t result in vomiting) and subside once your hormones settle.
The oestrogen in your pill can irritate your stomach lining, with some studies even suggesting it may slow down how quickly it empties, which can cause side effects like nausea.
4. Mood swings
If you have a history of anxiety, depression, or insomnia, you might find that these symptoms get worse when you’re on the pill.
Interestingly, for some, this can actually help improve low mood, especially if it’s linked to premenstrual syndrome (PMS). But it’s important to note that everyone reacts differently: one person might notice their mood lifts, while another may notice the opposite.
If you think the pill is affecting your mental health, it’s important to speak to your prescriber or GP for advice.
Weight gain is one of the most reported side effects of the pill, despite there being no evidence to support it. Any visible changes are likely down to water retention or bloating rather than fat gain, especially in the first few months as you adapt to the pill.
Oestrogen can cause your body to hold onto more fluid, making you feel puffy or swollen. This temporary fluid retention can make the scales go up slightly or your clothes feel tighter, even though you haven’t gained any fat.
Hormones also affect your digestive system, which is why some people experience increased bloating, gas, or changes in bowel movements.
If you already suffer from irritable bowel syndrome (IBS) or other gastrointestinal disorders, these symptoms can be more pronounced, as you’re more sensitive to any fluctuations in your hormones.
6. Sore breasts
Breast tenderness is a fairly common side effect when you first start taking the pill. It’s caused by the hormones (particularly oestrogen) affecting your breast tissue.
They might feel sore, swollen, or more sensitive than usual, similar to how they might feel before your period. Again, this should ease once you get used to the pill.
7. Acne
Just like with headaches and migraines, some contraceptive pills can help with acne, whereas others can cause it.
Combined pills can be effective at clearing up hormonal acne by balancing your hormones and reducing oil production in your skin. They’re even sometimes prescribed specifically for acne.
However, the mini pill can trigger or worsen breakouts, which is why they’re not usually recommended if you have hormonal acne.
“There are lots of different types and causes of acne. A good way to tell if your acne is hormone-related is by looking at where it appears. Hormonal breakouts typically show up on your chin, jawline, or lower cheeks, rather than across your whole face.
“While it can take two to three months for your skin to settle as your body adjusts to the hormones, persistent or worsening spots are a sign that this particular pill might not be right for you.
“Your prescriber or GP can help you switch to an alternative that's less likely to trigger acne or may even help improve your skin.”
Combined pill vs mini pill: which has the fewest side effects?
There’s no straightforward answer to which pill has fewer side effects, as everyone responds differently. The combined pill contains both oestrogen and progestogen, while the mini pill contains just progestogen.
Here’s how they compare when it comes to side effects:
Combined pill side effects
Mini pill side effects
More predictable periods with the seven-day break, so less chance of random spotting.
More chance of irregular bleeding due to the lack of oestrogen keeping your uterine lining stable.
Might cause nausea, headaches or migraines, and mood swings because of the oestrogen.
Less likely to cause nausea, headaches, migraines, or mood swings since there's no oestrogen.
Unlikely to cause acne and can even help clear it up.
More likely to make acne worse, especially hormonal acne.
When should you contact a doctor about your side effects?
“If side effects are still bothering you after three months, speak to your prescriber or GP for advice, as they may be able to recommend an alternative form of contraception.
“Blood clots are a rare but serious risk when taking the combined pill, affecting up to one in 1,000 people. Before prescribing the pill, your doctor, nurse, or pharmacist will check if you have any risk factors that might increase your chances of developing a clot.”
Claire Irwin, Prescribing Pharmacist at Chemist4U
It's important to know the symptoms of a blood clot so you can get help quickly if needed. Seek urgent medical attention if you experience any of these:
painful swelling, redness, or warmth in your leg (especially just one leg)
sudden chest pain or difficulty breathing
severe headache that comes on suddenly
problems with your vision, such as blurred or lost vision
coughing up blood
Long-term side effects of the contraceptive pill
The pill can slightly increase your risk of:
breast cancer
cervical cancer
This increased risk is very small. However, any increased risk goes back to normal within 10 years of stopping the pill.
On the other hand, taking the pill actually lowers your risk of developing:
womb (uterus) cancer
ovarian cancer
bowel cancer
What to avoid when on the birth control pill
Some medicines and supplements can affect how the pill works. These include:
Vaginal ring: a small, soft, plastic ring that’s placed inside your vagina that releases oestrogen and progestogen, just like the combined pill.
Contraceptive patch: this sticks to your skin, and it lasts for one week.
Contraceptive injection: this releases progestogen, like the mini pill, and lasts 8-13 weeks depending on the type.
Birth control implant: a small rod is placed under the skin in your upper arm that releases progestogen. It lasts up to three years.
IUD and IUS: the IUD (coil) releases copper to prevent sperm reaching the egg, while the IUS releases progestogen. Both are fitted through the cervix into the womb, similar to a smear test. The IUD lasts 5-10 years and the IUS lasts 3-5 years.
Condoms: a barrier method and the only contraception that protects against both pregnancy and STIs.
Waiting for a GP appointment or visiting a sexual health clinic for your contraceptive pill can be a hassle. That’s why we’re proud to offer the NHS Free Contraception Service, so you can get your regular pill or start a new one from the comfort of your own home, completely free.
Complete a simple online consultation, and one of our clinicians will arrange a phone call to make sure it’s right for you. This is also a great opportunity for you to ask any questions.
If you’re both happy, we’ll deliver your prescription quickly and discreetly to your door.
Ready to get started? Click the button below to get your free contraceptive pill with Chemist4U.
Frequently asked questions about contraceptive pill side effects
Can birth control make you infertile?
Birth control doesn’t cause infertility. While it might take a few months for your periods to get back to normal after stopping the pill, it won’t affect your ability to get pregnant in the long run.
Does birth control cause bloating?
The pill can cause bloating, especially in the first few months. This is due to the hormonal changes that cause your body to retain water.
Can the pill cause constipation?
Some people experience constipation with the pill due to the hormones slowing down your digestive system. Make sure to drink plenty of water, include fibre-rich foods in your diet, and stay active.
Why am I spotting on the pill?
Spotting on the pill is one of the most common side effects, especially when starting or switching. This is due to your body adjusting to the hormones. Missing pills or taking them at different times can also cause spotting.
Can the pill make you dizzy and nauseous?
Yes, some people can feel dizzy or sick when they start the pill, usually because of oestrogen. Taking your pill with food or before bed can help.
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