Aspirin – a tablet for inflammation and pain relief, and blood thinning

Aspirin – a tablet for inflammation and pain relief, and blood thinning

Aspirin is a tablet used to reduce pain, reduce fever, and thin the blood (to prevent serious cardiovascular conditions).

Generic name: aspirin (oral) [ AS-pir-in ]
Brand names: Many
Uses: Reduce pain, reduce fever, and thin the blood
Dose format: 75 mg; 300 mg; 325 mg; 500 mg; 1g
Drug classes: NSAID

What is aspirin?

Aspirin (acetylsalicylic acid) is a widely used medication prescribed at low doses to prevent blood clots, and taken at higher doses as an everyday painkiller for aches, pains, and flu symptoms.

It belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs), though its low-dose form is primarily classified and utilized for its antiplatelet (blood-thinning) properties.

How it works

At high doses, aspirin works by blocking cyclo-oxygenase (COX) enzymes, which stops the body from producing prostaglandins—the chemicals that trigger pain, swelling, and fever.

At lower doses, aspirin permanently inhibits platelet aggregation. By making blood cells “less sticky,” it prevents the formation of dangerous blood clots inside the arteries, reducing the workload and risk of ischemia (restricted blood flow) to the heart and brain.

Uses

Aspirin is used for people with:

• Mild to moderate pain (such as headaches, toothache, and period pain) or fever

• A history of cardiovascular disease, including previous heart attacks or stable angina

• Ischaemic stroke or transient ischaemic attack (TIA / mini-stroke) to prevent recurrence

• Certain pregnancy-related risks, such as preventing pre-eclampsia (under specialist guidance)

Dosage

The usual aspirin dose depends entirely on whether it is being used for daily cardiovascular protection or temporary pain relief:

• Low-dose (Antiplatelet): Typically 75 mg once daily (often increased to 300 mg immediately following an acute stroke or heart attack).

• High-dose (Pain relief/Fever): 325 mg to 650 mg every 4 to 6 hours as needed, up to a maximum of 4 g daily.

• Administration: Standard and dispersible tablets should be taken with or just after food to protect the stomach lining.

Note: Never give aspirin to children or adolescents under the age of 16 unless specifically prescribed by a doctor. It is linked to a rare but exceptionally serious condition called Reye’s syndrome.

Side-effects

Aspirin side effects vary based on the dosage and individual gastrointestinal tolerance.

• Indigestion, heartburn, or stomach aches

• Bleeding or bruising more easily than normal (including regular nosebleeds)

• Increased bleeding time for minor cuts

• Allergic reactions, particularly in individuals with pre-existing asthma

Serious side effects such as coughing up blood, dark or tarry stools, severe indigestion, or vomiting blood indicate gastrointestinal bleeding and require emergency medical attention.

Monitoring

Your doctor should monitor:

• Signs of gastrointestinal irritation or hidden bleeding (via full blood count tests)

• Kidney and liver function tests during long-term, high-dose regimens

• Blood pressure control, as poorly controlled hypertension increases the risk of bleeding complications

• Concomitant medication use to prevent dangerous interactions with other blood thinners (like warfarin or clopidogrel) or NSAIDs

Other resources

• NHS: About Low-Dose Aspirin – Medicines Guide

• BNF: Aspirin Monograph – British National Formulary

• NICE: Stroke and Ischaemic Attack Antiplatelet Indicator [IND133] – Clinical Indicator

• Mayo Clinic (USA): Aspirin (Oral Route) Patient Information