Phenindione

  • You will have been given an anticoagulant record book; read this, and always carry it with you.
  • You will need regular blood tests to check the level of phenindione in your blood - these blood tests are very important.
  • You should not begin a weight reducing diet without discussing it with your doctor first.
  • Alcohol should only be drunk in moderation.

About phenindione

Type of medicineAnticoagulant
Used forPrevention and treatment of harmful blood clots
Available asTablets

Phenindione works by reducing the effects of vitamin K which is a vitamin present in the body and essential in the process of blood-clotting. Reducing the effect of vitamin K prevents or treats the formation of harmful clots by thinning the blood and/or dissolving clots.

Before taking phenindione

Before taking phenindione make sure your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have a peptic (stomach) ulcer.
  • If you suffer from high blood pressure.
  • If you have had recent surgery, or are due for surgery in the near future.
  • If you suffer from liver or kidney problems.
  • If you have been diagnosed as having an infection of the heart.
  • If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines.
  • If you have ever had an allergic reaction to this or any other medicine.

How to take phenindione

  • Before beginning treatment, read the manufacturer's printed information leaflet.
  • You should have been given a treatment booklet with your tablets. Read and follow the instructions carefully before beginning treatment.
  • Take this medication exactly as directed by your doctor.
  • Try to take phenindione at the same time each day to avoid missing any doses.
  • If you forget to take a dose, take one as soon as you remember unless it is nearly time for your next dose. Do not take two doses at the same time to make up. If in doubt, speak to your pharmacist or doctor.

Getting the most from your treatment

  • Always attend your regular appointments with your doctor or anticoagulant clinic. You will need to have regular blood tests, especially during the first few weeks of treatment, to ensure that the dose of phenindione you are taking is correct for you. Your INR (International Normalised Ratio) is a measure of the ability of your blood to prevent clotting and shows the extent to which phenindione is working.
  • You should carry the treatment booklet you have been given with you at all times, ideally in your wallet or purse.
  • Before having any kind of surgery, including dental or emergency treatment, tell the doctor, dentist or surgeon you are taking phenindione and show the person carrying out the tests or treatment your treatment booklet.
  • Phenindione is used to prevent blood clots forming and therefore thins the blood so it is important that you take care not to knock, cut or bruise yourself while you are taking phenindione. Inform your doctor if you suffer any falls, blows or injuries. You should also take special care when brushing your teeth or shaving. Use a soft toothbrush, be gentle when using dental floss and if possible use an electric razor.
  • Changing your diet suddenly can affect your phenindione levels, especially if you begin to eat more vegetables and salad or if you change the amount of fatty foods you have been eating. You should not begin a weight reducing diet without discussing it with your doctor first.
  • Alcohol should only be drunk in moderation. Alcohol can also affect the levels of phenindione in your body.
  • Do not stop taking phenindione without speaking to your doctor first.
  • This medicine may colour your urine pink or orange. This is completely harmless and is no cause for concern.
  • If you buy any medicines, check with a pharmacist that they are safe to take with your other medicines.

Can phenindione cause problems?

Along with their useful effects all medicines can cause unwanted side effects which usually improve as your body adjusts to the new medicine. Speak with your doctor or pharmacist if any of the following side effects continue or become troublesome.

Common side-effects - these affect less than 1 in 10 people who take this medicineWhat can I do if I experience this
Unusual bruising, bleeding, blood in the urine, blackened stoolsSee your doctor - your dose will probably need to be reduced
DiarrhoeaDrink plenty of water to replace lost fluids
Feeling or being sickEat little and often. Stick to simple foods.
If you are sick drink plenty of liquid
Pink or orange coloured urineThis is harmless and no cause for concern
Skin rash, loss of hair, purple toesIf troublesome, speak to your doctor

Important: If you experience a severe skin rash, blistering, or yellowing of the skin and whites of the eyes, speak with your doctor immediately or go to your local accident and emergency department.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

How to store phenindione

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines


  • Never take more than the prescribed dose. If you suspect that you or someone else has taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out of date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

References

  • British National Formulary; 57th Edition (March 2009) British Medical Association and Royal Pharmaceutical Society of Great Britain, London (link to current BNF).
Comprehensive patient resources are available at www.patient.co.uk
© EMIS 2009DocID: 3262DocRef: dils2156Last Reviewed: 12 May 2009Version: 22
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