Reviewed by Usama Ali, MPharm (GPhC: 2224726). Last reviewed: April 2026.
The combined pill carries a small increased risk of blood clots: around 5 to 7 per 10,000 users per year, compared to 2 per 10,000 in non-users. For context, the risk during pregnancy is around 29 per 10,000.
The mini pill does not increase blood clot risk at all. It is a suitable alternative if clot risk is a concern.
Blood clots are one of the most common concerns people have about the combined pill. The concern is understandable, but the actual numbers are often misunderstood. Here is what the data says.
In women who do not use hormonal contraception and are not pregnant, about 2 in every 10,000 develop a venous blood clot (deep vein thrombosis or pulmonary embolism) per year. Among women taking a combined pill containing levonorgestrel (such as Microgynon or Rigevidon), that figure rises to approximately 5 to 7 per 10,000 per year. Among women taking pills containing desogestrel, gestodene, or drospirenone, the figure is around 9 to 12 per 10,000 per year. These figures come from the FSRH Combined Hormonal Contraception guideline.
To be clear: the risk is real, but it is small. For every 10,000 women taking a levonorgestrel combined pill for a year, about 5 to 7 will develop a clot. The vast majority will not.
| Pill type | Approximate VTE risk per 10,000 users per year |
|---|---|
| No hormonal contraception (baseline) | About 2 |
| Combined pill with levonorgestrel (Microgynon, Rigevidon) | 5 to 7 |
| Combined pill with desogestrel or gestodene (Marvelon, Femodene) | 9 to 12 |
| Combined pill with drospirenone (Yasmin, Lucette) | 9 to 12 |
| Mini pill (any type) | No increased risk |
| Pregnancy | About 29 |
| First 6 weeks after birth | About 300 to 400 |
The table shows why levonorgestrel pills like Microgynon are usually the first choice combined pill. They carry the lowest clot risk. If a different progestogen is used (such as drospirenone in Yasmin), it is because the clinical benefit (for example, improvement in acne or bloating) justifies the slightly higher risk.
Most people who take the combined pill will never develop a blood clot. But some factors increase your baseline risk, and your pharmacist checks all of these before prescribing.
Family history. If a first-degree relative (parent or sibling) had a venous blood clot under the age of 45, the combined pill is not usually recommended. Your pharmacist will ask about this during your consultation.
Personal history. If you have had a blood clot yourself, the combined pill is not suitable. The mini pill is the standard alternative.
Smoking. Smoking and the combined pill together significantly increase cardiovascular risk, particularly if you are over 35. If you smoke and are 35 or over, the combined pill is not prescribed. If you smoke and are under 35, the risk is assessed individually.
BMI. A BMI above 35 is a reason not to prescribe the combined pill, because obesity independently raises the risk of blood clots.
Immobility and surgery. Prolonged immobility (long flights, bed rest, major surgery) increases clot risk. Your surgeon or anaesthetist may advise stopping the combined pill 4 weeks before major surgery. The mini pill does not need to be stopped.
Age. The risk of blood clots increases with age. This is one reason why the combined pill is available through the PCS up to age 49 but not beyond.
These criteria come from the UK Medical Eligibility Criteria (UKMEC), the same framework used by GPs and sexual health clinics.
Blood clots are rare, but knowing the warning signs is important. Seek urgent medical help (call 999 or go to A&E) if you experience any of the following while taking the combined pill:
Deep vein thrombosis (DVT): painful swelling in one leg, usually the calf. The area may feel warm and look red or discoloured. This is different from normal muscle ache.
Pulmonary embolism (PE): sudden chest pain, difficulty breathing, or coughing up blood. A PE happens when a clot travels to the lungs. This is a medical emergency.
Stroke: a sudden severe headache unlike any you have had before, sudden confusion, difficulty speaking, sudden numbness or weakness on one side of the body, or sudden changes in your vision.
"We always explain the warning signs when we prescribe the combined pill for the first time," says Usama Ali, MPharm (GPhC: 2224726), pharmacist at Contraception Direct. "It is not about scaring you. It is about making sure you know what to look out for, so that if something did happen, you would recognise it quickly."
The mini pill (progestogen-only pill) does not contain oestrogen. It is the oestrogen in the combined pill that increases clot risk. That means the mini pill carries no increased risk of blood clots at all.
If blood clot risk is a concern for you, whether because of family history, personal risk factors, or simply peace of mind, the mini pill is a safe and effective alternative. It is over 99% effective with perfect use, just like the combined pill.
For a comparison of the two types, read our guide on combined pill vs mini pill.
Every time the combined pill is prescribed through the NHS Pharmacy Contraception Service, your pharmacist runs through the UKMEC checklist. They check your blood pressure, BMI, smoking status, migraine history, family history of blood clots, personal history of cardiovascular disease, and current medications.
If any of these raise a concern, the combined pill is not supplied. Instead, your pharmacist recommends the mini pill or refers you for further assessment if needed. This is the same process used by GPs and sexual health clinics.
For repeat supplies, your pharmacist reviews these factors again at each consultation. Blood pressure and BMI are rechecked regularly. If anything has changed, they adjust their recommendation.
It is worth remembering that unintended pregnancy also carries risks, and the risks of pregnancy are higher than the risks of taking the pill. Blood clot risk during pregnancy is around 29 per 10,000, compared to 5 to 7 per 10,000 on a levonorgestrel combined pill.
The combined pill has been used safely by millions of people for over 60 years. It is well studied, well understood, and well monitored. The role of your pharmacist is to make sure it is safe for you as an individual, not just as a population average.
If you have questions about your personal risk, book a free consultation with Contraception Direct. Your pharmacist can explain the numbers in the context of your own health and help you decide whether the combined pill or the mini pill is the better option for you.
Book a free phone consultation. Your pharmacist will review your personal risk factors and recommend the right option for you.
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