How to use aspirin

How to use aspirin

How to use aspirin

Dosage forms and strengths

Aspirin is available in the following forms and strengths:


  • Tablets (81mg, 325mg and 500mg)
  • Delayed-release tablets (162mg, 325mg and 500mg)
  • Chewable tablets (75mg and 81mg)
  • Enteric-coated tablets (81mg, 162mg, 325mg and 650mg)
  • Extended-release capsules (162.5mg)
  • Oral chewing gum (227mg)


  • Tablets (81mg, 325mg and 500mg)
  • Delayed-release tablets (162mg, 325mg and 500mg)
  • Chewable tablets (75mg and 81mg)
  • Enteric-coated tablets (81mg, 162mg, 325mg and 650mg)
  • Oral chewing gum (227mg)

At what dosages is the medication likely to be prescribed?

1. Adults

For the treatment of…

  • Fever and pain: Tablets can be taken orally at between 325mg and 650mg every 4 to 6 hours. Extended or delayed release tablet products may be taken orally at between 650mg and 1300mg every 8 hours. Dosages should not exceed 4g per day (24-hour period). A suppository of between 300mg and 600mg may be administered every 4 hours. Regular dosing is not recommended for more than 10 consecutive days at a time.
  • Acute coronary syndrome (unstable angina / chest pain and elevated risk of heart attack): For the treatment of acute symptoms chewable tablets at between 162mg and 325mg can be taken orally (within minutes of symptom onset). Alternatively, a suppository (of between 300mg and 600mg) may be safely administered if the sufferer isn’t able to be taken the medication orally. Used for secondary prevention purposes (controlled maintenance of symptoms following a cardiovascular event), tablets at 75mg to 81mg may be taken orally per day. Alternatively, between 81mg and 325mg may be taken orally per day if deemed safe by a medical doctor. Co-administered medications may apply in maintenance instances and can include ticagrelor (a platelet aggregation inhibitor), often prescribed at 81mg a day (taken orally). Other existing medical conditions will be taken into account before a dosage is prescribed.

For medical procedure use…

  • If aspirin is used ahead of a percutaneous transluminal coronary angioplasty (a non-surgical procedure for the treatment of narrowed coronary arteries), adjunctive aspirin therapy may be administered. Pre-procedural doses of between 163mg and 325mg (administered up to 2 hours beforehand) may be taken orally. Maintenance doses following the procedure may be prescribed at 81mg per day (or in doses between 81mg and 325mg per day), taken orally. Maintenance doses may be prescribed indefinitely.
  • Aspirin that is given following a CABG (coronary artery bypass graft) procedure is normally administered orally at between 75mg and 100mg (per single-dose). The dosage will be given 6 hours following the procedure and often maintained once a day for up to a year.
  • Ahead of a carotid endarterectomy procedure (a surgery to reduce the risk of stroke by correcting narrowing (stenosis) of the carotid or internal carotid artery), dosages may be given at between 75mg and 100mg (once a day). Daily dosages may be prescribed indefinitely following the procedure.

Aspirin may be prescribed for preventative treatment purposes in the following instances:

  • Stroke (ischemic and transient ischemic attack / TIA): Doses may be given orally at between 160mg and 325mg per day within 48 hours after a stroke is experienced. Thereafter, dosages may be given at between 75mg and 100mg per day. Extended-release aspirin may be given once daily for maintenance purposes at 162.5g.
  • Heart attack / cardiovascular disease: Individuals who show signs of an increased risk of a heart attack may be prescribed between 75mg and 100mg (per single dose) a day. A diabetic individuals (those with diabetes type 1) with an increased risk of heart attack can also be prescribed preventative dosages at between 75mg and 162mg per day. Extended-release forms may be given at 162.5mg (per single dose) a day too.
  • Osteoarthritis, arthritis, rheumatoid arthritis and systemic lupus erythematous: Dosages (of specific quantities as per standard strength availability) may be prescribed several times (i.e. in divided doses) but will not exceed 7.3g per day in order to achieve an anti-inflammatory effect. Dosages will be personalised by a treating physician and monitored so as to avoid the possible risk of developing salicylate toxicity.
  • Spondyloarthropathy: Dosages (of specific quantities as per standard strength availability) may be prescribed several times but will not exceed 7.3g per day in order to achieve an anti-inflammatory effect. Dosages will be personalised by a treating physician and serum concentrations within the blood will be monitored so as to avoid the possible risk of salicylate toxicity.
  • Colorectal cancer (off-label): Dosages may be given up to 600mg a day (taken orally for up to two years) to help decrease the hereditary risk of developing this condition – specifically Lynch syndrome. For primary prevention purposes, between 75mg and 325mg may be prescribed. Patients who are 50 years of age or older may be prescribed between 75mg and 100mg a day (to be taken in single dosages). Lower dosages are recommended for older individuals who may have an increased risk of cardiovascular disease, but a low risk of bleeding.
  • Preeclampsia (off-label): Low dosages are recommended once daily. These may be prescribed in the 75mg to 150mg range. Treatment may only commence around the 12th week of pregnancy and will be discontinued around 36 / 37 weeks. However, taking aspirin during pregnancy should ONLY be done when recommended by a doctor or gynaecologist for this reason.

For preventative purposes, aspirin dosages may help to reduce the risk of death due to a heart attack in individuals susceptible to or have a history of coronary artery disease, heart attack, and chronic or unstable angina. Where rapid preventative action is required, medical doctors may prescribe immediate-release aspirin (in oral tablets or suppository form). Alternatively, extended-release forms of aspirin may be used where acute treatment is not as applicable.

2. Paediatric

For the treatment of…

  • Fever and pain (not due to viral illness – this is VERY important):
    • Children younger than 12 years of age (including infants / babies) weighing less than 50kg – Dosages may be given at between 10mg and 15mg per kilogram every 4 to 6 hours (taken orally). No more than 90mg or 4g per kilogram will be given per day.
    • Children 12 years of age and older weighing 50kg or more – Dosages may be given at between 325g and 650mg every 4 to 6 hours a day. Extended or delayed-release aspirin may also be given at between 650mg and 1300mg every 8 hours. Dosages exceeding 4g per day (24 hours) will not be given. Regular dosing is not likely to be recommended for longer than 10 consecutive days. Alternatively, suppositories may be given at between 300mg to 600mg every 4 hours.
  • Juvenile rheumatoid arthritis:
    • Children who weigh less than 25kg – Dosages may be given at between 60mg and 90mg (per kilogram) every 4 to 6 hours (taken orally) to help achieve an anti-inflammatory effect. Dosages can also be given at between 80mg and 100mg every 6 to 8 hours. Dosages may be adjusted to maintain this effect as needed.
    • Children who weigh more than 25kg - Dosages may be given at between 2.4g and 3.6g per day (taken orally) to help achieve an anti-inflammatory effect. Dosages may be adjusted to maintain this effect as needed.
  • Kawasaki disease:
    • Febrile (acute) phase – During the period of time whereby a child displays symptoms of fever which is showing signs of abating, dosages may be given at between 80mg and 100mg (per kilogram) every 6 hours for up to 14 days. Moderate doses can also be given at between 30mg and 50mg (per kilogram) per day every 6 hours for no longer than 14 days. Dosages are given until a fever has subsided and remained so for between 48 and 72 hours.
    • Maintenance – Thereafter, aspirin may be given as a single dose of between 3mg and 5mg per kilogram (weight of the child) a day as needed.
  • Thrombotic / thromboembolic disorder:
    • Dosages may be given at between 1mg and 5mg per kilogram of the child’s body weight per day (taken orally). Dosages may be given daily for up to 2 years.
  • Rheumatic fever:
    • Dosages may be given at 100mg (per kilogram) per day, broken up into at least 4 or 5 doses. Dosages may be recommended for up to 2 weeks and then reduced to between 60mg and 70mg (per kilogram) per day for between 3 and 6 weeks (or as needed).

A dosage of 200mg per kilogram of weight is considered toxic and will not be recommended or prescribed. Extended-release capsules may not be prescribed to or recommended for children under the age of 18 as safety has not been conclusively proven through research.

Factors to consider before taking aspirin

In order to avoid adverse interactions and side-effects, it is best to ensure that the following types of conditions are taken into consideration before administering aspirin for any treatment purpose:

  • Known allergies to aspirin or other ingredients contained in combination medications (containing aspirin)
  • Asthma (or recently experienced an asthma attack)
  • Blood clotting, platelet and bleeding problems (including a history of bleeding in the stomach or intestines) or disorders (like haemophilia)
  • Anaemia
  • Nose polyps
  • Rhinitis or seasonal allergies
  • Impairments of the kidneys or liver (including kidney or liver disease)
  • Ulcers of the stomach or bowel
  • Gastrointestinal diseases, such as gastritis and peptic (stomach) ulcer disease (active)
  • Frequent heartburn, acid reflux or stomach troubles (upset stomach or pain)
  • Gout
  • Hypertension (high blood pressure)
  • Heart problems like heart disease or congestive heart failure
  • A known sensitivity to salicylates or tartrazine dyes (which is sometimes used in aspirin containing medication products)
  • Dehydration (aspirin that is taken during a dehydrated state may elevate one’s risk of a heart attack)

If any of the above-mentioned conditions apply, adverse reactions may occur.

If a doctor is considering aspirin for any treatment purpose, he or she will also wish to know if a patient…

  • Has any history of allergies (including medications foods and other substances) and what types of symptoms are experienced following exposure (such as hives, rash, itching, swelling – especially the face, lips or throat; coughing, wheezing or shortness of breath).
  • Is taking any other medications (such as NSAIDs or others which may contain aspirin as an ingredient) – all prescription, over-the-counter, supplements (including vitamins or nutritional varieties) and herbal or natural products should be disclosed to a doctor.
  • Is pregnant
  • Is breastfeeding / nursing

A doctor will be cautious regarding viral infections in children and teenagers due to the risk of Reye’s syndrome, which can be life-threatening if used during such illnesses.

How to take aspirin correctly

Factors to consider regarding the administration of aspirin:

  • Orally taken tablets or capsules: Aspirin is best taken with food or a large quantity (full glass) of water – this helps to alleviate any possible gastrointestinal troubles. If a person is susceptible to adverse reactions, lower dosages can be recommended or prescribed. Tablets (including extended-release capsules) should be swallowed whole and not chewed, broken or crushed. Enteric-coated forms should never be crushed or broken either – the coating is normally a polymer barrier that helps to prevent the disintegration of the product within the gastric system. Such medication is intended to be broken down and released once in the intestines and not in more acid prone areas of the body (such as the stomach). Chewable immediate - release tablets are suitable for treatment where a rapid onset of action is required (such as in the case of a heart attack). These can be chewed or swallowed whole. Extended / delayed release forms may be recommended to be taken at the same time if used daily. Extended-release aspirin should not be taken at least 2 hours before consuming alcohol (or at least 1 hour afterwards).
  • Suppository / rectal: Aspirin suppositories will need to be removed from plastic packets or wrappings and inserted as far as possible into the rectum. If the suppository is soft it can be briefly chilled in a refrigerator or run under cold water before being inserted. In order for insertion to take place comfortably, a person should lie down on their side and raise the top knee towards the chest. Once inserted, the suppository will be held in place for a few moments. It is best to allow at least 15 minutes before standing upright. Hands should be washed thoroughly with warm water and soap following insertion.

It should take anywhere between 5 and 30 minutes for a dose of aspirin to begin taking effect. Chewable or non-coated forms (except delayed or extended-release) begin to take effect faster.

Aspirin should always be taken as directed – either by a medical doctor recommending treatment or via the medication label. Increasing or decreasing dosages without the consent of a medical professional is not advisable.

If required a medical doctor may recommend periodic monitoring while treatment with aspirin is active. Monitoring will include assessment for signs of bruising or bleeding (which can occur more easily), as well as liver and kidney function impairments. Bleeding that is unusual or excessive is a concern and if this occurs, treatment using aspirin may need to be amended or changed. Monitoring checks may involve blood tests.

If aspirin treatment has been recommended for daily use, it is not advisable to discontinue or change dosages without the express consent of a medical doctor.

What should I do if I miss a dose of aspirin?

If a person is on a dosing schedule and misses one, the next dosage can be taken immediately or as soon as it is remembered. If remembered close to the time of the next scheduled dose, the missed one should be skipped – not doubled up with the next scheduled dose. Multiple doses should never be taken at the same time.

It is a good idea to ensure that all healthcare providers are aware that aspirin is being taken should any further pharmacological recommendations be made at any time – this includes all doctors, dentists, pharmacists or nurses.

Aspirin and surgery

Typically, when any elective surgical procedure is being considered (including dental procedures), a doctor will ask about aspirin use. As aspirin can increase a person’s susceptibility to bleeding, discontinued use (short-term – usually at least 1 to 2 weeks prior) may be requested to avoid this complication during and shortly after a procedure.

Aspirin storage and expiry dates

Aspirin should always be stored at room temperature and kept away from heat, light and moisture. Suppositories can be stored in a cool and dry place or refrigerated (not kept in the freezer). All aspirin medications must be kept well out of reach of children and pets.

If any aspirin product (tablet, capsule, suppository etc.) has a vinegar-like smell when opened, it should not be used at all.

Aspirin products that are expired or unused should never be discarded down a drain or flushed down a toilet as sewage systems cannot remove medications from the water and this may end up being pumped into rivers and lakes. It is best to consult a pharmacist or medical doctor with regards to the safe disposal of unused or expired aspirin. Some areas / cities have existing medication ‘take-back programmes’ which can assist with collecting unwanted medications for their safe disposal. If such a programme is not available, disposal along with household rubbish or trash is acceptable. The FDA (U.S. Food and Drug Administration) recommends mixing unused medications with substances such as cat litter, dirt or used coffee grounds before throwing these away in the trash. The mixture should be disposed of in a sealed container. (4)


4. US Food and Drug Administration. March - June 2018. Disposal of unused medicines: What you should know: [Accessed 22.06.2018]

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