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Aspirin 300mg tablets – patient leaflet, side effects, dosage

Updated:
Key facts
Status:
Pharmacy medicine (P)
Medicine strength:
300 mg
Contains active substance:

Patient leaflet - Aspirin 300 mg tablets

1 What Aspirin tablets are and what they are used for 2 What you need to know before you take Aspirin tablets

  • are planning to become pregnant
  • have heavy bleeding during your periods
  • have a history of stomach ulcers

3 How to take Aspirin tablets

  • have chronic respiratory disease
  • have hypertension

4 Possible side effects

  • are taking deferasirox (a medicine to remove excess iron from the body).

5 How to store Aspirin tablets

6 Contents of the pack and other information 1 What Aspirin tablets are and what they are used for

Other medicines and Aspirin tablets

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines, including medicines obtained without a prescription. Especially:

Aspirin tablets belong to a group of medicines which have analgesic (pain relieving), anti-inflammatory (inflammation reducing) and anti-pyretic (temperature reducing) properties.

  • warfarin, coumarin, heparin, dipyridamole and clopidogrel (used to prevent blood clotting)

These tablets may be used for the relief of:

  • metoclopramide or domperidone (to prevent sickness)
  • headache, toothache, migraine, neuralgia (nerve pain), sore throat or period pains.
  • diuretics (“water tablets”) such as spironolactone, furosemide, acetazolamide (to treat high blood pressure)
  • symptoms of influenza, feverishness, rheumatic pains (pain, stiffness and discomfort of the joints), sciatica (nerve pain of the leg/back), lumbago (lower back pain), fibrositis (muscular rheumatism), muscular aches and pains.
  • medicines which make your urine more alkaline such as antacids, cit rates
  • probenecid (to treat gout)
  • methotrexate (to treat some cancers, psoriasis and rheumatic disease)

The tablets may also be used to prevent blood clots especially after a heart attack or in patients with unstable angina or reduced blood flow in the brain.

  • sulfonylureas (antidiabetics)
  • phenytoin or sodium valproate (to treat epilepsy)
  • corticosteroids (to suppress the immune system)

2 What you need to know before you take Aspirin tablets

Do not take Aspirin tablets and tell your doctor if you:

  • mifepristone (to induce abortion)
  • other non-steroidal anti-inflammatory drugs - NSAIDs (such as ibuprofen or naproxen)
  • are allergic to aspirin, salicylates or non-steroidal anti-inflammatory drugs (NSAIDs), or other ingredients of this medicine. You may have developed difficulty breathing, a runny nose, itchy skin or swelling after taking aspirin or a NSAID previously (see section 6)
  • metamizole (substance to decrease pain and fever) may reduce the effect of aspirin on platelet aggregation (blood cells sticking together and forming a blood clot), when taken at the same time. Therefore, this combination should be used with caution in patients taking low dose aspirin for cardioprotection
  • have a stomach ulcer or a history of ulcers or indigestion
  • vancomycin (medicines which can cause hearing problems)
  • have nasal polyps associated with asthma
  • medicines to treat high blood pressure such as ACE inhibitors (e.g. enalapril, lisinopril, perindopril), Calcium channel blockers (e.g. amlodipine, diltiazem, nifedipine)
  • have haemophilia or other blood clotting disorders or are taking medicines to thin the blood
  • have severe liver or severe kidney problems or severe heart failure
  • SSRIs such as sertraline or paroxetine (medicines to treat depression)
  • are in the last 3 months of pregnancy
  • varicella (chickenpox) vaccine. Aspirin should be avoided for 6 weeks after vaccination
  • are a child under 16 years old
  • are taking methotrexate (15mg a week).

    Continued over page Continued top of next column

    Aspirin Tablets

    300mg x 28 (UK)

    Date Sent:

    04/02/20

    Technologist:

    T. Hull

    Technically Approved

  • herbal medicines containing ginkgo biloba
  • digoxin (to treat heart problems)
  • lithium (to treat depression)
  • acetazolamide (to treat glaucoma)
  • cyclosporin, tacrolimus (used to prevent organ rejection)
  • alcohol.

    Tell your doctor if you notice any of the following side effects or notice any other effects not listed:

    Common: may affect up to 1 in 10 people

    • Increase in the number of nose bleeds, longer bleeding time or notice that you bruise more easily or have more infections talk to your doctor
    • Indigestion.

Pregnancy and breast-feeding

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine. Avoid taking Aspirin tablets during pregnancy, especially in the last 3 months of pregnancy or whilst breast-feeding.

Surgery and tests

If you need to have an operation including having your teeth removed or blood and urine tests, tell your doctor or dentist you are taking this medicine.

3 How to take Aspirin tablets

Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure. Avoid alcohol whilst taking this medicine.

Uncommon: may affect up to 1 in 100 people

  • Runny nose
  • Itchy skin rash caused by allergic reaction- pale or red irregular raised patches with severe itching (hives).

Rare: may affect up to 1 in 1,000 people

  • Anaemia, changes in numbers and types of blood cells and enzymes seen in blood tests
  • Difficulty breathing or wheezing, worsening of asthma
  • Heavy periods
  • Irregular red patches on the skin of the hands and arms (erythema multiforme)
  • Disorder characterised by blood spots, bruising and discolouring to skin (Purpura)
  • Bleeding in the skin, mucous membranes
  • Red tender lumps developing under the skin (Erythema nodosum).

Swallow the tablets with a glass of water.

Doses:

Adults, including the elderly:

The recommended dose is 1 or 2 tablets every 3 to 4 hours as required. No more than 12 tablets in any 24 hour period.

For prevention of blood clots:

The recommended dose is 1 tablet once a day.

Use in children and adolescents

Aspirin tablets are not recommended for use in children and adolescents younger than 16 years

If you take more Aspirin tablets than you should

If you (or someone else) swallow a lot of tablets at the same time, or you think a child may have swallowed any, contact your nearest hospital casualty department or tell your doctor immediately. Symptoms of an overdose include ringing in the ears, spinning sensation, fast breathing rate, changes in some of the chemicals in the body, heart failure, changes in body temperature resulting in dehydration, restlessness, fits, hallucination (seeing or hearing things that are not there), headache, hearing problems, confusion, feeling or being sick, stomach pain or coma.

If you forget to take Aspirin tablets

Do not take a double dose to make up for a forgotten dose. If you forget to take a dose, take it as soon as you remember it and then take the next dose at the right time. Do not take more than one dose in any 4 hour period.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4 Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

If you notice any of the following serious side effects, stop taking Aspirin tablets and contact a doctor immediately:

  • Difficulty breathing
  • Severe allergic reactions (blistered skin, swelling of the face, lips, throat or tongue, difficulty breathing, worsening of asthma, shock)
  • Severe rash involving reddening, peeling and swelling of the skin that resembles severe burns (Lyells syndrome) or severe rash, blisters, or red patches on the skin (Stevens-Johnson syndrome)
  • Bleeding on the brain (sudden severe headache, fit, changes in vision, speaking, understanding or coordination, weakness in an arm or leg)
  • Stomach ulcers or bleeding which can be severe (you may develop bloody or black tarry stools, severe stomach pain and vomit blood), stomach irritation (mild stomach pain, heartburn and feeling or being sick) and inflammation of the liver
  • Salicylism - if you take large doses for a long time you may develop symp-toms of salicylism, these include: dizziness, ringing or buzzing in the ear, deafness, sweating, feeling or being sick, headache and confusion
  • Hepatitis (inflammation of the liver causing yellowing of the skin or eyes or tiredness, pain in abdomen, joint or muscles).

Continued top of next column

50987587 BBBA7547

Not known: frequency cannot be estimated from the available data

  • Gout (high levels of uric acid in the blood)- causing crystals to deposit in joints of hands/feet causing pain (Hyperuricaemia)
  • Nosebleeds, bleeding of the gums, which may be prolonged. (Please advise doctor or dentist if surgery is planned)
  • Reduction of red blood cells which can make the skin pale and cause weakness or breathlessness (anaemia). Reduction in red blood cells which cause pale yellow skin and weakness or breathlessness (haemolytic anaemia), blood disorder resulting in impaired blood clotting leading to an increased risk of bleeding, reduced number in red and white blood cells, blood loss, elevated blood enzymes levels (as seen in blood test)
  • Headache
  • Feeling of dizziness or spinning
  • Hearing loss; ringing or buzzing in the ears
  • Liver problems
  • Reduced kidney function.

Additional side effects in children

Aspirin may be associated with the development of a condition called Reye’s Syndrome, which causes severe liver and brain damage.

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme Website: www.mhra. gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

By reporting side effects you can help provide more information on the safety of this medicine.

5 How to store Aspirin tablets

Keep this medicine out of the sight and reach of children

Store the tablets below 25°C in a dry place.

Do not use Aspirin tablets after the expiry date stated on the label/ carton/bottle. The expiry date refers to the last day of that month. Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.

6 Contents of the pack and other information What Aspirin tablets contain

  • The active substance (the ingredient that makes the tablets work) is 300mg aspirin (also known as acetylsalicylic acid).
  • The other ingredients are maize starch, talc (E553(b)).

What Aspirin tablets look like and contents of the pack

Aspirin tablets are white, circular, biconvex uncoated tablets marked ‘’ASPIRIN 300mg’’ on one face and the letters ‘’C’’ and ‘’AO’’ on either side of a central division line on the reverse. Alternatively, the reverse is blank.

Pack sizes are 28 tablets.

Marketing Authorisation Holder and Manufacturer

Accord, Barnstaple, EX32 8NS, UK.

This leaflet was last revised in May 2020

Version 6 12.12.2019 German GTIN 14 (incorporating PZN): Cartons and label leaflets only

(labels only when specified)

Aspirin Tablets

300mg x 28 (UK)

Date Sent:

04/02/20

Technologist:

T. Hull

Technically Approved

About this document

Source: MHRA - Medicines and Healthcare products Regulatory Agency (products.mhra.gov.uk) · Marketing authorisation: PL 00142/1248

Last revision stated in the text: May 2020 · MHRA data as of 13 October 2026

What the sections and the side effect frequencies mean: How to read a patient leaflet

Found a mistake? Tell us on the contact page.

The information on this site does not replace the advice of a doctor or pharmacist.

Facts about Aspirin 300 mg tablets

What these facts mean

Prescription needed?? No, but it is sold only in pharmacies (P)
Active substance? Aspirin
Strength? 300 mg
Pharmaceutical form? Oral tablet
White, circular, biconvex uncoated tablets impressed "ASPIRIN 300mg" around the circumference on one face, and the identifying letters "C" and "AO" on either side of a central division line on the reverse; or, as an alternative, tablets impressed "ASPIRIN 300mg" around the circumference on one face.
How is it taken? Oral
Excipients? Maize starch,, Talc (E553(b))
Pack sizes 28 tablet
Is it available?? Listed as available (NHS Dictionary of Medicines and Devices – not a record of current supplies)
Shelf life? Shelf-life
3 years
Shelf-life after dilution/reconstitution
Not applicable.
Shelf-life after first opening
Not applicable.
Storage Store below 25°C in a dry place.
Drug group (ATC)? Other analgesics and antipyretics:
  1. N Nervous system drugs
    1. N02 Analgesics
      1. N02B Other analgesics and antipyretics
        1. N02BA Salicylic acid and derivatives, analgesics and antipyretics
          1. N02BA01 acetylsalicylic acid
Marketing authorisation? PL 00142/1248 (first authorised 28 July 2026)
Marketing authorisation holder? Accord-UK Ltd
Codes? GTIN 5012617001450 · BNF 04070100

Sources: the MHRA product information (products.mhra.gov.uk) and the NHS Dictionary of Medicines and Devices (dm+d), release 11.1.0 of 9 November 2026, NHS Business Services Authority. Contains public sector information licensed under the Open Government Licence v3.0.