Thrombosis and haemostasis

When you take anticoagulants, your blood will not clot as easily and you may find that you bleed more than normal. You may notice that when you cut yourself, you bleed a little longer. Nosebleeds, bleeding gums and heavier periods are all more likely when you take anticoagulants. Continue to take your anticoagulant and contact the clinic if you experience any of these or something else you are concerned about. Find out more information about periods and anticoagulation.

If you notice any blood in your urine or poo or black poo, you must seek medical attention. If you develop any bruises that appear without any obvious cause, or if the bruising spreads, feels hard or darker and more painful, please seek medical attention.

Attend the nearest emergency department if you experience any of the following:

• nosebleeds lasting longer than 15 minutes
• blood when coughing or vomiting
• if you hit your head, face or tummy (abdomen) or experience severe headaches
• if you experience any serious bleeding that does not stop or slow down with first aid measures such as applying pressure and raising the affected area

Any symptoms of serious bleeding must be treated urgently

Please contact your anticoagulation clinic as soon as possible. Your anticoagulant medication may need to be paused before surgery. We usually require two weeks’ notice ahead of the surgery to create a personalised plan for you.

It is important to let your dentist know you are taking anticoagulants before any dental procedure, due to the risk of bleeding. You may need to have a blood test before starting treatment.

It is safe to travel while on anticoagulants. Please ensure you take enough supply of medication for the duration of your trip. If you take warfarin or acenocoumarol, take your dosing slip with you in case you need to have a test or need treatment while abroad. In addition, please inform your anticoagulation clinic when you are travelling and how long you will be away for. The clinic will advise if you need a blood test while away. Please note, if you are away for more than three months, you will need to be managed by a local anticoagulation clinic. Please ensure your travel insurance provides adequate protection.

If you have had a blood clot or stroke within the last six weeks, please contact the anticoagulation clinic to discuss your travel plans.

Stay as mobile as possible while you are flying and keep well hydrated. Take your anticoagulant at the equivalent UK time where possible, allowing for changing time zones.  If unsure, contact the clinic for guidance.

Your anticoagulation medication shouldn’t stop you from being physically active. However, please take extra care as some activities put you at higher risk of injury and/or bleeding. This includes all contact sports like football, rugby, cricket, skiing and hockey. If you are unsure, please discuss this with the anticoagulation clinic.

If you suffer a head injury, such as falling and hitting your head, or experience a blow to the head, seek medical help without delay to rule out internal bleeding which may not be immediately obvious.

It is not advisable to have a tattoo or body piercing if you’re on blood-thinning medication as it can increase the risk of bleeding or infection. Please speak to your anticoagulation clinic or GP if you decide to go ahead.

Usually, small cuts or scrapes will stop bleeding when pressure is applied to them. If bleeding does not stop after more than 10 minutes of first aid, seek medical attention.

If you suffer a head injury, such as falling and hitting your head, or experience a blow to the head, seek medical help without delay to rule out internal bleeding which may not be immediately obvious.

Please speak to the anticoagulation clinic before starting these if you take warfarin or acenocoumarol. If you have had a thrombosis (blood clot) in the past, combined contraception (oestrogen and progesterone) or oral HRT (tablet) should be avoided. Alternative options are available, please discuss with your GP.

Please inform us immediately when you become pregnant or if you are planning a pregnancy. Most oral anticoagulants are not safe for pregnant women or birthing people.

An international normalised ratio (INR) blood test measures how long it takes for your blood to clot. It is used to monitor blood clotting in people taking some anticoagulants. We use INR results to determine the correct dose of warfarin or acenocoumarol for you.

After your blood test, we will inform you of the new dose of warfarin or acenocoumarol you need to take (if necessary) by the end of the next working day. Result slips will be posted unless you state another preference. The dosing letter is also available to view on MyChart (called ‘AVS’). For more information about MyChart registration and support, please see MyChart section below.

We will only call patients for dose changes. Therefore, if you do not hear from the clinic, please continue to take the current dose of warfarin or acenocoumarol. If you do not receive your test results by post within five workings days, please contact the clinic (see contact details below).

The frequency of your international normalised ratio (INR) blood tests will depend on the stability of your INR level. Some patients will require tests every one to two weeks. This time frame will be extended if your results stabilise. The maximum period between INR blood tests is 12 weeks.

Your INR result, dosing instructions and next test date will be communicated to you by letter in the post. You can request that these results are emailed to you instead. It is also possible to view your next scheduled appointment for a blood test on MyChart. If you do not have MyChart, please see below for more information. If you do not receive your test results by post within five workings days, please contact the clinic. See ‘How do I book an INR blood test and where can I have it?’ below for further information.

Always test on the day that your appointment is scheduled. Update the clinic if you are unable to test on your scheduled day as your appointment will need to be rescheduled. If you test on a different date without informing us, we may not receive your test result.

Once you are informed of your next test date, you will need to book your blood test online (or use walk-in service where available).

King’s College Hospital patients:

King’s College Hospital, Golden Jubilee Wing, Denmark Hill – book via Swiftqueue
Opening hours: Monday to Friday, 7.30am to 5.45pm

Tessa Jowell Health Centre, 72H East Dulwich Grove, SE22 8EY – book via Swiftqueue
Opening hours: Monday to Friday, 7.30 to 3.45pm

Princess Royal University Hospital patients:

Princess Royal University Hospital, Outpatient Department C, Ground Floor – walk-in only
Opening hours: Monday to Friday, 9am to 4pm

Beckenham Beacon Hospital, Phlebotomy Department, Ground Floor – book via Swiftqueue
Opening hours: Monday to Thursday, 7.30am to 4.30pm; Friday 8am to 4.30pm

Orpington Hospital, Phlebotomy Department, Ground Floor – book via Swiftqueue
Opening hours: Monday to Friday 7.30am to 4.30pm

Queen Mary’s Hospital, Sidcup – book via Swiftqueue
Opening hours: Monday to Thursday: 8.45am to 4.30pm, Friday: 9.15am to 1pm then 1.30pm to 4.30pm

If you do not have access to a computer or a smart phone, please contact the anticoagulation clinic for further steps.

Yes, you should still attend and explain that you take warfarin or acenocoumarol. Please take your hospital number if possible.

If you are starting any new medications or supplements (including painkillers, vitamins, food supplements, natural and herbal remedies) please tell the anticoagulation clinic by phone or email, stating the name, dose and duration (if known) of the new medication. If you are due your INR blood test soon, please make a note of any medication changes on your slip. We will usually ask that you have an INR reading taken between three and five days of starting the new medication. It is a good idea to notify us when you stop a medication or change a dose too as this can also impact your INR control.

If you accidently miss a dose of warfarin or acenocoumarol, take the missed dose as soon as you remember. If you do not remember until the next day, skip the missed dose and take your next dose at the usual time. Never take two doses at the same time or on the same day. Do not take extra medication unless you are instructed to by the anticoagulation clinic.

Make a note of the date that you missed your warfarin or acenocoumarol and let the clinic know on your test slip.

If you have a mechanical valve, antiphospholipid syndrome or have had a blood clot or stroke in the last three months, contact the clinic as soon as possible to update us that you have missed your dose.

Always ensure you have at least a one week supply of your medication. Please contact your GP for a repeat prescription of your warfarin or acenocoumarol, allowing time for them to process the request. We can send a copy of your most recent anticoagulation slip to your GP at your request. If you need an emergency out of hours prescription contact NHS 111. Do not stop taking warfarin or acenocoumarol without speaking to the anticoagulation team.

Drinking alcohol can interact with warfarin and acenocoumarol to increase the INR which can increase the risk of bleeding.

Government recommendations state to drink no more than 14 units of alcohol per week, spread over at least 3 days. This equates to 6 medium glasses of wine or 6 pints of 4% beer. While there is no safe level of alcohol, not exceeding these guidelines lowers the risk of alcohol to your health.

If you exceed this quantity, please inform your anticoagulation clinic as soon as possible to arrange a blood test.

If you accidently miss a dose, take the missed dose as soon as you remember. If you do not remember until the next day, skip the missed dose and take your next dose at the usual time. Never take two doses at the same time. Do not take extra medication unless you are instructed to by the anticoagulation clinic.

Do not stop taking your medication without speaking to the anticoagulation team. Please contact your GP for a repeat prescription of your medication well in advance, allowing time for them to process the request. If your GP is unable to prescribe this medication, contact the anticoagulation clinic as early as possible and we will try to resolve you prescription issue. If you need an emergency out of hours prescription contact NHS 111.

MyChart is an online web portal and mobile app that connects our patients to their medical information at King’s College Hospital and Guy’s and St Thomas’ NHS Foundation Trusts.

With MyChart, our patients’ health records are stored in one, easy place. You will be able to check your INR using MyChart 24 hours after testing.

Find out more information about how to access MyChart.

If you cancel your INR appointment through MyChart, please contact us at the clinic to rebook by either emailing or leaving us a voice message.

Please contact our MyChart helpdesk on 020 3299 4618 or [email protected] (Monday to Friday, 9am to 5pm)