What it is used for
- Preventing and treating blood clots in the legs and lungs
- Used during some hospital procedures, surgery and dialysis
- Helping manage certain heart attacks and unstable angina
- Keeping intravenous lines from clotting (in low concentrations)
How it works
Heparin activates the body's natural clot-blocking proteins, switching off several clotting factors. This rapidly reduces the blood's ability to clot, and its effect can be measured and reversed if needed, which is useful in hospital settings.
How it is taken
Supplied as a liquid given by injection under the skin or, in hospital, as a continuous drip into a vein. It is almost always given and monitored by healthcare staff, often with blood tests to guide the amount. It is used exactly as the medical team directs.
No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.
Common side effects
- Bruising or irritation at the injection site
- Easy bruising
- Minor bleeding such as nosebleeds
- Mild rise in certain liver blood tests
Serious effects — get help
- Heavy or uncontrolled bleeding, black/tarry stools, blood in urine, coughing up or vomiting blood - emergency
- Sudden severe headache, weakness or confusion (possible brain bleed) - emergency
- A rare immune reaction causing a fall in platelets with new clots - the team monitors for this
- Severe allergic reaction: facial or throat swelling, trouble breathing
If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.
Interactions to watch
- Other blood thinners and antiplatelets including aspirin and clopidogrel
- Anti-inflammatory painkillers (NSAIDs)
- Certain heart and blood-pressure medicines
- Spinal or epidural procedures (timing carefully managed)
Who should take care
- Tell the team about any bleeding disorders, recent surgery, stomach ulcers or previous heparin reactions
- Report any kidney or liver problems
- Used in pregnancy only under specialist supervision
- Because it is hospital-administered, follow staff instructions and report any unusual bleeding or bruising promptly