Indications
Acetylsalicylic Acid (Aspirin) is used in two main ways. In low doses (usually 75 to 150 mg a day) it is prescribed to prevent blood clots in people who have had a heart attack, stroke or mini-stroke, who have stable or unstable angina, or after heart procedures such as stenting or bypass surgery. In higher doses it relieves mild to moderate pain (headache, toothache, period pain, muscle pain), reduces fever, and eases inflammation.
How It Works
Aspirin permanently blocks an enzyme called cyclo-oxygenase (COX). In platelets (tiny blood cells that start clotting) this stops the production of thromboxane, making platelets less sticky for their whole lifespan of about 7 to 10 days. At higher doses it also reduces prostaglandins, chemicals that cause pain, fever and inflammation.
Dosage and Administration
- To prevent clots: take the low dose your doctor prescribes, usually 75 mg once a day, after food. Do not stop without asking your doctor.
- For pain or fever (adults and children over 16): 300 to 900 mg every 4 to 6 hours as needed, after food, maximum 4 g in 24 hours.
- Swallow enteric-coated tablets whole; dispersible tablets are dissolved in water.
Interactions
- Higher bleeding risk with Warfarin, Apixaban, Rivaroxaban, Heparin, Clopidogrel, Ticagrelor, SSRIs (such as Sertraline) and corticosteroids.
- Ibuprofen and other NSAIDs increase stomach bleeding risk and Ibuprofen may reduce aspirin’s heart protection; take Ibuprofen at least 30 minutes after low-dose aspirin, or ask your pharmacist.
- Can increase Methotrexate toxicity and reduce the effect of some blood pressure medicines and diuretics.
- Alcohol increases the risk of stomach bleeding.
Contraindications
- Children and teenagers under 16 years (risk of Reye’s syndrome), unless a specialist prescribes it.
- Active stomach or duodenal ulcer, or history of ulcer bleeding.
- Bleeding disorders such as haemophilia.
- Allergy or asthma triggered by aspirin or other NSAIDs.
- Severe kidney, liver or heart failure.
- Last 3 months of pregnancy at pain-relief doses.
Side Effects
Common effects include indigestion, heartburn, nausea and bruising more easily. Less often: stomach ulcers or bleeding, nosebleeds, ringing in the ears (at high doses), skin rash and worsening asthma.
Get urgent medical help if you vomit blood or material like coffee grounds, pass black tarry stools, have severe stomach pain, sudden wheezing or difficulty breathing, swelling of the face or throat, or signs of a stroke or bleeding in the brain such as sudden severe headache, weakness or confusion.
Pregnancy and Lactation
Avoid pain-relief doses in pregnancy, especially in the last 3 months, as they may harm the baby’s heart and kidneys and increase bleeding at delivery. A doctor may prescribe low-dose aspirin in pregnancy to reduce the risk of pre-eclampsia: take it only as directed. Avoid regular use during breastfeeding unless a doctor advises; occasional low doses are usually acceptable.
Precautions and Warnings
- Tell your doctor or dentist that you take aspirin before any surgery or tooth extraction.
- Take care if you have asthma, gout, kidney or liver problems, or are older.
- Do not start daily aspirin for prevention without a doctor’s advice; for many healthy people the bleeding risk outweighs the benefit.
Overdose
Aspirin overdose is dangerous. Signs include ringing in the ears, fast breathing, vomiting, sweating, fever, confusion and drowsiness. Get emergency medical help immediately, even if the person seems well.
Therapeutic Class
Antiplatelet agent; non-steroidal anti-inflammatory drug (salicylate) and analgesic.
Storage
Store below 30°C in a dry place, away from light and moisture. Keep out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.