Anticoagulants are prescribed to prevent blood clots from forming and causing serious life-threatening events, such as strokes.

  1. Prescribed to prevent blood clots.
  2. Lower the risk of strokes, DVT, heart attacks and pulmonary embolisms
  3. Available in tablets, capsules and injections.

If you are concerned about the risks of blood clots, you can speak to one of our registered clinicians via our online video consultation service. They are available from 9.30am-4.30pm, five days a week.

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Product information

What are anticoagulants?

Anticoagulants are medications prescribed to prevent the formation of blood clots, which can lead to serious health risks from strokes, heart attacks, DVT (deep vein thrombosis) and pulmonary embolisms. They are available in many forms, and can be prescribed to treat people with various health conditions where blood clots are a risk.

What are blood clots?

Blood clots can be life threatening and require immediate treatment to prevent them from occurring. Clotting is part of the body’s natural healing process; it stops bleeding by binding together platelets (found in blood cells) where a wound is present. 

Blood clots do not always form when they should, however, with parts breaking off and blocking arteries around some of the body’s major organs. It’s a situation that causes strokes (clots around the brain) heart attacks (around the heart), DVT (around the legs, pelvis or arms) and pulmonary embolism (around the lungs). Symptoms of a blood clot include cramping of the legs or arms, a throbbing sensation, redness or swelling of the affected area, breathlessness, chest pain and a cough (that sometimes produces blood). 

What causes blood clots?

There are many causes, but your risks of getting a blood clot are heightened if you are sedentary (for example, following an operation),  if you are obese, are a smoker, if you take combined contraceptives or if you have previously suffered from a blood clot. As well as taking anticoagulants, preventative measures can be highly effective, and reduce the need for medication. These include regular exercise, avoiding becoming dehydrated, losing weight (if relevant), stopping smoking and wearing flight socks during air travel (available from most pharmacies).

What is a stroke? 

Strokes occur when the body’s blood supply is cut off from the brain, or if a blood vessel is weaker and subsequently haemorrhages. Symptoms include the face dropping to one side (including the eye and mouth), being unable to lift your arms, and slurred speech. Treatment for a stroke will depend on the part of the brain that is affected, but will likely require medication. 

Preventative measures, such as anticoagulants, will be used as a preventative measure if you are at risk. Recovery is a long-term process, and often has a significant impact on peoples’ lives, due to the injuries to the brain. For some people, functioning independently once more can take a considerable amount of time, and in many cases a full recovery is not made. Local authorities are able to provide full reablement services that can help with the day to day challenges of post stroke care, and support groups can provide emotional support.

What is a heart attack?

Heart attacks are caused by a blockage of blood flow to the heart, with profound, life threatening consequences. CHD (coronary heart disease) is the primary cause of heart attacks, where the arteries leading to the heart become blocked by cholesterol (also referred to as plaque). 

Symptoms of heart attacks include chest pain (often described as a heavy weight or squeezing pain that spreads from the chest to the neck, jaw, arm and back), breathing difficulties, weakness, light-headedness and anxiety

How is a heart attack treated?

In terms of treatment, chewing an aspirin whilst waiting for an ambulance to arrive is advisable, as it helps to thin the blood. Once in hospital, treatment will depend on how serious the condition is. Medication may be used to dissolve the blood clot in many cases, but surgery to remove the blockage may also be required. 

Similarly to strokes, recovery can be a long process and its duration depends on the damage done to the heart and arteries. In some cases, you will be able to return to work within a matter of a few weeks. In other instances, it may be many months. Anticoagulants are prescribed if the cause of the heart attack is a blood clot, whereas statins are prescribed if cholesterol is the cause. Making lifestyle changes is key to recovery, however. Gradually increasing exercise, eating a healthy diet, quitting smoking and cutting down on alcohol consumption can all help, along with managing your stress and anxiety levels.

What is deep vein thrombosis?

DVT (deep vein thrombosis) is when a vein is blocked by a blood clot, usually in the leg. It can be life-threatening and may require immediate medical assistance. The symptoms of DVT are a throbbing and swelling in one or both legs (most often the thigh or calf), warm skin that is painful, red and darkened around the area affected, and swollen or painful veins. In rare cases, it can occur in other parts of the body, such as the stomach, where the symptoms described above will present. 

Diagnosis of DVT requires either an X-ray or an ultrasound, which can identify where the blockage is. Treatment can then begin immediately, with blood thinning medications (anticoagulants) in tablet form or as injections administered. Treatment with these medications for DVT will usually last around three months. 

If these medications prove ineffective, or aren’t suitable, a filter can be fitted to reduce the risk of the clot affecting vital organs. A new treatment may also be provided, where the clot can be filtered out or broken up with a tube placed in a small vein, with use of anticoagulants for up to three months afterwards. Lifestyle changes are also recommended to reduce the risks of  symptoms recurring. These include regular walking, raising the leg when resting and avoiding long haul flights for a few weeks after treatment.

What are pulmonary embolisms?

Pulmonary embolisms are blockages to the lungs caused by blood clots. They are life threatening, and require immediate medical attention. Symptoms may differ from case to case, but a pain in the chest or upper back, coughing up blood and difficulties catching your breath are common. Other symptoms include a rapid heartbeat and loss of consciousness. 

Treatment usually involves injecting anticoagulants into the body while test results are being processed. These injections will continue for five days after diagnosis has occurred, followed by three months of anticoagulant tablets. Provided the clot has been treated quickly, you can expect to make a full recovery. 

Lifestyle changes and practices can prevent pulmonary embolisms from occurring in the first place. Regular exercise, changes to diet, quitting smoking, and cutting down on alcohol are central to recovery. Maintaining good posture when sitting, wearing loose clothing, bending and stretching your legs regularly and pressing the balls of your feet to the floor can also help to reduce the risk of developing pulmonary embolisms.

If you have any concerns relating to the conditions listed above, or would like to discuss anticoagulants with a GMC-registered clinician, you can access our online video consultation service, which is available from 9.30am until 4.30pm, five days a week. Our  clinicians can also issue fit notes and referral to specialists for treatment, where appropriate.  

Page last reviewed:  18/06/2020
Side effects and warnings

What side effects do anticoagulants have?

Side effects may differ from product to product. One of the most commonly prescribed is warfarin, which may cause the following: allergic reactions, rashes, alopecia, diarrhoea, discolouration or ‘bruising’ of the skin, yellowing of your eyes and skin and changes in the amount or appearance of your urine.

If you experience any of the following you should seek immediate medical assistance as it may be a sign of an allergic reaction or other serious issue: unexplained nose bleeds, black or red faeces, dark red or brown urine, fever, nausea, vomiting, a painful skin rash, hair loss or diarrhoea.

Are anticoagulants safe to take with other medications?

It’s very important that you inform your doctor of any medications you are currently or have recently taking, or any health issues you have or are prone to. Only then will your prescribing doctor be able to properly ascertain whether this treatment is safe for you. 

Warfarin should be avoided if any of the following relate to you: you are allergic to warfarin; you are pregnant, breast-feeding or planning on becoming pregnant; have liver or kidney problems; have had an infection of the lining of your heart or a condition which causes bleeding or makes you bruise easily; high blood pressure; are taking St John’s Wort; are within 24 hours of having surgery or giving birth.

The following treatments may make warfarin unsuitable for use: medicines for heart problems, including amiodarone, quinidine and propafenone, non-steroidal anti-inflammatory drugs (NSAIDs) including ibuprofen and aspirin, medicines that lower cholesterol, such as bezafibrate, gemfibrozil, clofibrate and cholestyramine, antibiotics, including erythromycin, co-trimoxazole or norfloxacin, vitamin k supplements and miconazole gel for fungal infections, such as thrush.

You should also avoid drinking large quantities of alcohol as well as avoiding consumption of cranberry juice during treatment.

What types of anticoagulants are there?

Almost all anticoagulants come in tablet or capsule form, with the exception of heparin, which is available by injection. Warfarin is the most commonly prescribed blood thinner, but newer types are available, including apixaban, edoxaban, rivaroxaban and dabigatran.

Page last reviewed:  18/06/2020
Questions and Answers

Are anticoagulants safe for use during pregnancy or while breastfeeding? 

Before you start treatment with any anticoagulant, it’s imperative that you inform your doctor if you are pregnant, thinking of becoming pregnant or suspect you may be pregnant. Warfarin is safe to take whilst breastfeeding.

Will anticoagulants affect my ability to drive? 

Warfarin should not affect your ability to drive or operate any heavy machinery.

How long does it take for anticoagulants to have an effect?

As everyone reacts differently to this treatment, it is not possible to predict exactly how long it will take before you find the right dosage for you, but warfarin should start to become effective after approximately three days. Blood tests are the only way to measure its effects.

Can I buy anticoagulants over the counter?

No. This treatment is available by prescription only. 

How can I buy anticoagulants online?

If you are concerned about a blood clot, our GMC registered clinicians can discuss anticoagulants with you via our online video consultation service. You can book an appointment with them between 9.30am and 4.30pm, Monday to Friday. They can also provide referral to specialists for treatment and fit notes, where appropriate.  

Page last reviewed:  18/06/2020

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