ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.
Overview
Its effect is checked with blood tests and wears off quickly when stopped.
What it's used for
- Treating clots and heart attacks in the hospital
- Preventing clots during surgery, dialysis, and hospital stays
How to take it
- Given by a health care worker as a shot under the skin or by IV.
Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.
Side effects
Common side effects
- Bruising
- Bleeding at injection sites
Call 911Vomiting blood, coughing up blood, or bleeding that won't stop
Call your provider todayNew clots or skin damage at shot sites, especially 5 to 10 days after starting (possible HIT)
Warnings
- Platelet counts are checked for heparin-induced thrombocytopenia (HIT).
Other medicines, foods, and alcohol
- Other blood thinners, aspirin, and NSAIDs raise bleeding risk.
Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.
Pregnancy and breastfeeding
Used in pregnancy when needed.
Missed doses, overdose, and storage
If you miss a dose
Not applicable: it's given by health care workers.
If someone takes too much
Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.
Storing it
Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.
Conditions it's used for
Sources
- DailyMed: FDA drug label for Heparin (U.S. National Library of Medicine)
- MedlinePlus: Drugs, herbs, and supplements
- FDA: Drugs@FDA
Last updated 2026-11-13.