People taking one of Britain's most commonly prescribed blood thinners have been reminded to avoid two types of drink that could lead to a dangerous situation. Recent reports suggest more than 2.5 million people take this medication across England alone.

Warfarin is categorised as an "anticoagulant" medicine, as described by the NHS website, which is used to make blood flow through veins more easily. This means that blood will be less likely to form a dangerous clot that could lead to potentially life-threatening issues like a stroke, heart attack or a pulmonary embolism.

Doctors may prescribe warfarin to treat blood clots and help prevent future blood clots if you've had one previously. People who have had conditions such as an irregular heartbeat, deep vein thrombosis or a pulmonary embolism may be considered for this medication.

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People tend to take this tablet once a day and will need regular blood tests to make sure the dosage is working correctly for them. The NHS has a warning on its website regarding these risks, ensuring the public understands the potential dangers associated with this medication and certain food and drink items.

A spokesperson said: "While warfarin has enormous benefits, the downside is that it can make you bleed more than normal. This is because while you're taking warfarin, your blood will not clot as easily. Apart from the risk of bleeding, warfarin is a very safe medicine. It's safe to take for a long time, even many years."

• bleeding for a little longer than usual if you cut yourself


• occasional nosebleeds (that last for less than 10 minutes)


• bleeding from your gums when you brush your teeth


• bruises that happen easily and take longer than usual to fade


• a mild rash


• hair loss

Occasionally, you can have serious bleeding from taking warfarin. This is where you bleed suddenly or without a cut or injury, or bleeding will not stop. This can be dangerous and needs urgent medical attention.

According to the NHS website, managing food and diet is crucial for people taking warfarin. Sticking to a healthy and stable diet means patients are likely to stay on the same dose of warfarin.

The NHS says: "Any big changes in what you eat or drink can change how your body responds to warfarin. Speak to your doctor or nurse before changing what you eat – for example, before you go on a diet to lose weight."

People are told that foods rich in vitamin K play a crucial role in determining how well the drug works. Foods like green, leafy vegetables, egg yolks, mature cheeses, avocados, and olive oil are some of the sources that people need to monitor closely.

"It's important that you eat foods containing vitamin K," the health service added. "So, rather than leaving them out of your diet, make sure you eat similar amounts of them regularly."

As part of the diet rules, the NHS stresses that two types of fruit juice should also be avoided, and this information should be included on the medication's leaflet. A spokesperson said: "Do not drink cranberry or grapefruit juice while you're taking warfarin. It can increase the effect of your medicine and put you at higher risk of bleeding."

Grapefruit and cranberries contain naturally occurring compounds that inhibit cytochrome, an enzyme found in the small intestine and liver. This results in elevated medication levels building up in the bloodstream, with the drug remaining in the system longer than the label states, which could lead to an unintentional overdose or make side effects last longer and feel worse.

People are warned off drinking these juices when they are prescribed other medications as well, such as statins, for the same reason. Speak to your doctor if you want to know any other specific foods or drinks that could interact with the medication prescribed.