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What is aspirin?

Aspirin is an anti-platelet drug often prescribed for people with MPNs. Aspirin is classified as a non-steroidal anti-inflammatory (NSAID) drug which means that it reduces inflammation but does not contain steroids. Aspirin is a drug that is very familiar to most people as it is often taken for fevers or headaches, but it also has other qualities. It has anti-platelet effects that reduce the risk of a heart attack or stroke in people at increased risk of vascular events. It is usually prescribed at a dose of 100 mg daily for patients with MPNs in Australia.

How does aspirin work?

Aspirin is often prescribed by haematologists for people with MPNs because it helps to prevent development of thrombosis (blood clots) by reducing the ‘stickiness’ of platelets. Aspirin blocks an enzyme called cyclooxygenase within platelets and helps stop platelets sticking to each other and to plaques within the walls of blood vessels and thereby reduces risk of blood clot (thrombus) formation within the blood stream.

How can taking aspirin help me?

People with MPNs have what is called ‘sticky blood’, meaning that people with MPNs are at increased risk of developing a thrombosis (blood clot) in their arteries (e.g. stroke or heart attack) or in their veins (e.g. deep vein thrombosis or pulmonary emboli). The ‘blood stickiness’ is due to an increase both in the number of blood cells and the tendency of these cells to stick to each other and to the blood vessel wall. Aspirin makes platelets less likely to stick to each other and the blood vessel wall. It does not alter the number of platelets or other blood cells.

Aspirin may be recommended by your haematologist as the sole therapy for your MPN or in conjunction with venesections or cytoreductive therapy (e.g. hydroxycarbamide or interferon alpha).

For some low-risk people with essential thrombocythaemia (ET) aspirin may not be recommended.

Aspirin may not be suitable for patients with low platelet numbers (thrombocytopenia), bleeding problems or those on an anticoagulant (e.g rivaroxaban, apixaban or warfarin) or alternative anti-platelet medication (e.g clopidogrel), or those with an aspirin-allergy.

Recommended dosage

Your haematologist will advise you how much and how often to take aspirin.

The most common dose prescribed in Australia is 100 mg once daily but occasionally a higher (e.g twice daily) or lower dose may be recommended. Frequently missing doses (non-compliance) impacts on the effectiveness of aspirin and may increase the risk of disease-related complications. Follow directions on the package or prescription label carefully. Ask your doctor or pharmacist to explain any part of the instructions that you do not understand.

For the coated aspirin preparations (e.g Cartia) it is recommended that you do not break, crush or chew the tablets. You should take them with a glass of water and they can be taken with or without food.

If you forget a dose of aspirin, take it as soon as you remember. However, if the next dose is due within 12 hours, skip the missed dose and take the next dose at the normal time. Do not take a double dose to make up for the dose you have missed.

Non-compliance – It is important that you follow the directions precisely. Failure to do so may increase your risk of vascular and thrombotic disease related complications.

Are there any side effects?


Approximately 1–10% of people taking aspirin may experience some of these side-effects:

  • Indigestion or stomach discomfort
  • Bleeding and easy bruising:
    • Gastrointestinal
    • Mucocutaneous (mucous membranes (e.g. gums) and skin)
  • Asthma exacerbation (tightness in chest, difficulty breathing)


Severe adverse effects, other than bleeding, are rare but can include allergic reactions, nausea and vomiting and Reye’s syndrome in children.

Interactions with other medications or vitamins, herbal supplements or remedies

Always provide the names of medicines prescribed for you as well as any over-the-counter medications (e.g vitamins, herbal supplements or remedies) to the health care team who are treating you. It can be very helpful to carry a list of the names and dosages of all your medicines to show to your haematologist at appointments.  The MPN AA has a wallet card which provides for medications to be listed.

Aspirin can interact with some other drugs, and can increase the gastrointestinal side effects of alcohol. Please inform your doctor if you consume alcoholic drinks.

The most important interactions are with other anti-platelet and anticoagulant medications including:

  • Clopidogrel
  • Non-steroidal anti-inflammatories (NSAID) e.g. Naprosyn, Voltaren
  • Anticoagulants (e.g. rivaroxaban, apixaban, warfarin)

Other medications and supplements can increase risk of bleeding so please discuss this with your haematologist.

Some over-the-counter cold and pain medications contain aspirin. Please check with your pharmacist or doctor prior to taking.

Frequently asked questions

What if I have other medical conditions?

Please ensure you discuss with your haematologist any conditions that increase your risk of adverse effects from aspirin such as aspirin allergy, bleeding disorders or gastrointestinal disorders.
Please also inform your doctor if you are pregnant or currently breastfeeding.

What if I need to have a medical procedure?

It is usually recommended to stop taking aspirin for seven days prior to invasive surgical procedures to minimise bleeding. Please ensure you discuss whether this is necessary with the doctor or dentist performing the procedure and your haematologist.

Can I have vaccinations such as the flu and COVID-19 jabs while taking aspirin?

You can have most vaccinations including the flu and COVID-19 vaccines whilst taking aspirin.

COVID-19 – Can I take antivirals while on aspirin?

If you test positive for COVID-19, you may be eligible for antiviral therapy. The antiviral most suitable for you will depend on what other medications you are taking and your kidney function. Treatment must be commenced within 5 days of symptom onset, or as soon as possible if you have no symptoms but test positive. Please contact your GP or haematologist to arrange antiviral therapy immediately if required.

What can I do to help myself if I have an MPN?

 It’s important to take good care of yourself. There are many things you can do to feel better.

  • Good nutrition is important. Eat a balanced diet including lots of fresh fruit and vegetables, lean protein and whole grains.
  • Drink plenty of water and prevent dehydration by avoiding excessive alcohol and caffeinated drinks.
  • Maintain a normal weight and maintain your muscle mass to help keep your cholesterol and blood sugar within normal limits.
  • Exercise is very beneficial for people with MPNs and helps to fight fatigue. Before starting on any new programme, check with your GP or haematologist and start slowly and gently.
  • Stop smoking. Ask your GP if you need help.
  • Consider wellness activities such as yoga, aerobic activity, strength training, meditation, massages, support groups, improved nutrition etc. An international study of hundreds of MPN patients showed wellness activities had a pattern of decreased levels of symptom burden, fatigue, depression, and a higher quality of life for MPN patients. (Survey of integrative medicine in myeloproliferative neoplasms – the SIMM study).

More information on living well with an MPN is available at www.mpnallianceaustralia.org.au

General advice

This is intended as general information about taking aspirin, or as a reference for people already taking this medication. It is important that in addition to this information, you read the information provided with your medicine and discuss any concerns with your general practitioner or haematologist.

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