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Direct oral anticoagulants (DOACs)
Understand health
Vitamins and supplements to avoid with heart medicines
BHF Senior Dietitian Tracy Parker explains which vitamins and supplements to watch out for if you take blood pressure tablets, blood-thinning medicines or statins.
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Page updated:
It’s easy to assume that nutritional supplements like vitamins, minerals, antioxidants, herbal products and other food‑based supplements are fine to take, especially when they’re marketed as a ‘natural’ way to support heart health.
But natural does not always mean safe, and supplements like St Johns wort, garlic and CoQ10 plus a range of vitamins are not automatically risk free.
Most people do not need supplements unless they have a diagnosed deficiency and a doctor has prescribed something specific, like iron.
The only routine recommendation is vitamin D during the colder months, when there's less sunlight.
Supplements can also interact with prescribed heart medications. Some may make your treatment less effective, while others can increase side effects.
This is important if you take medicines for high blood pressure or high cholesterol, or if you're taking blood‑thinning medicines.
UK Government guidance is clear: nutritional supplements are not recommended for preventing or managing cardiovascular disease (CVD).
Research does not show any heart‑health benefits, and high doses can even be harmful.
For most people, a healthy, balanced diet gives the heart everything it needs.
If you’re thinking about starting a supplement, or you already take one, let your doctor or pharmacist know.
They can check whether you need it and make sure it’s safe to take with your prescribed medication.
- Learn the foundations of healthy eating for a healthy heart.
How do vitamins and supplements affect heart medicines?
Certain vitamins and supplements can change the effectiveness of medications.
Here we list the key ones to look out for with 3 types of heart medicines: blood pressure tablets, blood-thinning medicines and statins.
1. Blood pressure medicines
Many common supplements can interfere with blood pressure medicines, such as:
Sometimes supplements make these medicines less effective, which can cause your blood pressure to rise or fall unexpectedly.
St John’s wort
St John’s wort is a herbal supplement marketed as a natural mood booster. It’s widely available, but also well‑known for causing drug interactions.
This is because it speeds up liver enzymes (particularly CYP3A4) that break down many medicines.
St John’s wort can make some blood pressure medicines, such as calcium channel blockers like amlodipine, less effective. This can make it harder to manage your blood pressure.
Garlic
Some research suggests that garlic supplements, especially at high doses, may slightly lower blood pressure, particularly in people who have high blood pressure. However, the evidence is not strong enough to support any guidelines recommending it.
If you take prescribed blood pressure medicines, garlic supplements could lower your blood pressure more than intended.
Liquorice root
Liquorice root can raise blood pressure by affecting the body’s salt balance, leading to fluid retention. This can work against blood pressure medicine, worsening high blood pressure.
2. Blood-thinning medicines
Some supplements can interfere with blood-thinners such as:
- anticoagulants, like warfarin
- direct oral anticoagulants (DOACs), such as apixaban
- antiplatelet medicines like aspirin or clopidogrel.
They can do this by either increasing the risk of bleeding or increasing the risk of clots.
Vitamin K
Vitamin K is essential for bone health and also helps blood to clot.
Foods naturally high in vitamin K, like liver, Brussels sprouts, broccoli and other green vegetables, as well as vitamin K supplements, can affect how the anticoagulant warfarin works.
Too much vitamin K can make warfarin less effective, so the blood clots more easily. Too little vitamin K can mean the blood does not clot enough.
That’s why people taking warfarin are advised to keep their dietary vitamin K intake consistent and avoid vitamin K supplements.
- Learn more about how warfarin works and its side effects.
Vitamin E
Vitamin E is often promoted as an antioxidant that might protect the heart. However, clinical trials have not shown any benefits to heart health.
Some evidence also suggests that long-term, high-dose vitamin E supplementation may increase the risk of bleeding, especially if you take blood‑thinning medicines such as anticoagulants, DOACs or antiplatelets.
UK Government guidance does not recommend vitamin E to reduce the risk of CVD.
St John’s wort
St John’s wort also interacts with blood-thinners by speeding up how the body breaks them down. This makes the medicines less effective and increases the risk of clotting.
UK advice is not to take St John’s wort if you’re also taking anticoagulants, DOACs or antiplatelets.
This matches wider UK Government guidance that St John’s wort interacts with many heart medicines.
Omega‑3 supplements
Fish oil capsules, omega‑3 blends, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) products are often promoted for improving heart health, cholesterol and inflammation.
However, large clinical trials have shown no benefit from taking omega‑3 supplements to prevent heart attack or stroke.
Because of this, UK Government guidance does not recommend omega‑3 supplements for preventing CVD or lowering cholesterol.
Prescription‑strength EPA is only used in specific cases to lower triglycerides and is not the same as over‑the‑counter fish oil capsules.
At high doses, omega‑3 supplements may also increase the risk of bleeding. If you take blood‑thinning medicines, using both together may raise your bleeding risk. These blood-thinners include anticoagulants, DOACs and antiplatelets.
3. Statins
Some common supplements can interfere with how common statins like atorvastatin, pravastatin and simvastatin work.
Vitamin B3
Vitamin B3 is also called niacin or nicotinamide.
Some people take high‑dose niacin supplements because they've heard it can help lower cholesterol.
Early research suggested that niacin could reduce ‘bad’ LDL cholesterol, raise ‘good’ HDL cholesterol and lower triglycerides, leading to its use with statins.
However, more recent large studies have shown that while niacin can lower LDL cholesterol, taking it with a statin does not reduce the risk of CVD or stroke.
In some trials, niacin supplements were linked to more side effects, including a higher risk of cardiovascular events and death.
UK Government guidance is clear that vitamin B3 is not recommended for lowering cholesterol or reducing cardiovascular risk.
St John’s wort
St John’s wort is not recommended if you take statins.
This is because it can lower the amount of statin in your blood, making it less effective at lowering cholesterol.
CoQ10 enzymes
CoQ10 (Co-enzyme Q10) is sold for ‘energy production’ and for people who experience muscle aches while taking statins. However, the evidence is mixed, and CoQ10 has not been shown to reliably help people continue with statin treatment or reduce muscle symptoms.
UK Government guidance is clear that people should not take CoQ10 to help them continue taking statin treatment.
- Learn more about CoQ10 supplements.
Vitamin D
Vitamin D is important for bone and muscle health. Some people also take it in the hope that it will reduce statin‑related muscle aches.
However, studies have not shown that taking vitamin D helps with statin‑related muscle aches, even in people who have low vitamin D levels. UK Government advice is not to take vitamin D for this reason.
- Find out when to take vitamin D.
Guide to medicine interactions
| Blood pressure medicines | Blood-thinning medicines | Statins | |
|---|---|---|---|
| St John's wort | Some types less effective | Less effective; increases risk of clots | Less effective |
| Garlic (high dose) | Can lower blood pressure too much | Slight increase in bleeding risk | |
| Liquorice root | Raises blood pressure and counters blood pressure medicines | ||
| Vitamin K | Reduces effectiveness of warfarin | ||
| Vitamin E | Increases bleeding risk | ||
| Omega-3 (high dose) | Increases bleeding risk | ||
| Vitamin B3 (niacin) | No added benefit; increases side effects | ||
| CoQ10 | May ease muscle pain but evidence is lacking |
How do you get nutrients without supplements?
There is little evidence to support claims that supplements improve heart health.
Supplements may be necessary in some situations for some people, but the best way to get the nutrients your heart needs is through a balanced diet.
When you eat a diet rich in fruits, vegetables, fish and whole grains, you get a mix of carbohydrates, fibre, protein, healthy fats, vitamins, minerals and antioxidants that work together to support heart health.
Individual supplements cannot provide this on their own.
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