Aspirin — NZ Medication Guide | KiwiMeds
✅ Reviewed by a Registered Pharmacist NZ | Last updated: May 2026 | This information is for educational purposes only and does not replace advice from your doctor or pharmacist.
What is Aspirin?
Aspirin (acetylsalicylic acid) is a medicine with multiple uses — pain relief at standard doses, and heart attack and stroke prevention at low doses (75–100mg daily). Low-dose aspirin is widely prescribed in New Zealand for cardiovascular risk reduction.
What is it used for?
Low-dose aspirin (75–100mg daily) is used to prevent blood clots in people who have had a heart attack, stroke, TIA (mini-stroke), or who have established cardiovascular disease. It is also used in some people at high risk of a first cardiovascular event. At higher doses (500mg–1000mg), aspirin relieves pain, fever, and inflammation.
How does it work?
Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes, which produce thromboxane A2 in platelets. This reduces platelet aggregation (clumping together), making blood less likely to clot. This antiplatelet effect lasts for the lifetime of the platelet (7–10 days), which is why even a low daily dose provides lasting protection.
How to take it
Low-dose aspirin (75–100mg) is taken once daily, usually in the morning with food or a glass of milk to reduce stomach irritation. Take it as directed by your doctor. Do not take low-dose aspirin for pain relief — it is not effective at this dose for pain.
Common side effects
Common side effects of low-dose aspirin include stomach upset and nausea (taking with food helps), heartburn, and increased risk of bleeding (easy bruising, longer bleeding from cuts).
Serious side effects to watch for
Serious side effects include gastrointestinal bleeding (black or tarry stools, vomiting blood — seek immediate care), major bleeding events, and aspirin-sensitive asthma (aspirin can trigger wheeze in susceptible people). Aspirin must not be given to children under 12 due to risk of Reye’s syndrome.
Important drug interactions
Increased bleeding risk when combined with other anticoagulants (warfarin, apixaban), other antiplatelets (clopidogrel), and NSAIDs. Ibuprofen and naproxen can interfere with aspirin’s antiplatelet effect if taken together — separate doses by at least 2 hours. Aspirin can increase methotrexate toxicity.
Things to avoid
Avoid other NSAIDs (ibuprofen, naproxen) regularly — they compete with aspirin and increase bleeding risk. Avoid if you have active stomach ulcers without medical guidance. Avoid in children under 12. Avoid excessive alcohol — increases bleeding risk.
NZ-specific information
Low-dose aspirin is fully funded by Pharmac for cardiovascular prevention. Available as Cartia (100mg) and generic 100mg tablets. Note: recent guidelines have reduced enthusiasm for low-dose aspirin as primary prevention (preventing a first heart attack) due to bleeding risks — it is mainly recommended for secondary prevention (after a heart attack or stroke).
Frequently asked questions
Can I take aspirin for a headache? Low-dose aspirin (75–100mg) is not effective for pain relief. For headaches, use paracetamol or ibuprofen. Should I stop aspirin before surgery? Discuss with your surgeon and cardiologist — stopping aspirin abruptly before surgery can increase cardiovascular risk. Usually a decision is made on a case-by-case basis.
💬 Always talk to your pharmacist or doctor for advice specific to you. This guide is for general information only and does not replace a professional consultation.
Related medications
Related: Ibuprofen, Paracetamol. Condition: Atrial Fibrillation, Stroke.
References & Further Information
The following New Zealand and international resources were used to inform this page: