Heparin sodium: what it does and how to use it safely

Heparin sodium is a fast-acting blood thinner used in hospitals to stop clots forming or growing. It works within minutes when given by IV and is often used for deep vein thrombosis (DVT), pulmonary embolism (PE), during dialysis, and around some surgeries or procedures. If someone mentioned “heparin” to you, they likely mean this salt form—practical, immediate, and closely monitored.

How heparin is given and monitored

There are two common ways to use heparin: unfractionated heparin (UFH) given IV or by subcutaneous injection, and low-molecular-weight heparin (LMWH, e.g., enoxaparin) given as a subcutaneous shot. UFH given through an IV infusion needs regular blood tests called aPTT to keep dosing in the safe range. LMWH usually doesn’t need routine aPTT checks but may require anti-Xa testing in pregnancy, obesity, kidney disease, or when dosing is uncertain.

Practical tips for injections and IV use

If you or a caregiver will give subcutaneous shots at home, rotate injection sites (abdomen or thigh), clean the area, pinch the skin, inject slowly, and don’t rub the site afterward. Keep the injection site clean and watch for growing redness or swelling. For IV use, only trained staff should start and adjust the infusion based on labs—never try to change an IV rate without instructions.

Know the common side effects: bleeding is the biggest risk, from easy bruising to heavier bleeding. Call a provider if you notice large bruises, blood in urine or stool, black stools, severe headache, or sudden weakness. A less common but serious problem is heparin-induced thrombocytopenia (HIT). HIT causes a drop in platelets and can paradoxically increase clotting risk—look for new bruising, tiny red spots under the skin, or unexpected clot symptoms, and report them immediately.

Interactions matter. Combining heparin with NSAIDs, aspirin, or other blood thinners raises bleeding risk. Heparin is often used to bridge people starting warfarin; that needs careful timing and monitoring by a clinician. If you’re on other meds or herbal supplements, tell your healthcare team before starting heparin.

Special groups: in pregnancy, UFH and LMWH are commonly chosen because they don’t cross the placenta. Kidney disease affects LMWH clearance, so dosing adjustments or choice of UFH may be needed. Older adults often need close monitoring because they bleed more easily.

Storage and handling are simple: keep unopened vials or prefilled syringes at room temperature away from light, and follow expiration dates. Dispose of needles and syringes in a proper sharps container.

If you have questions about why heparin was chosen, how long it will be used, or what tests you’ll get, ask your care team. Understanding the plan—route, monitoring, and signs that need urgent care—will keep treatment safer and less stressful for you and the people caring for you.