A low-molecular-weight heparin injection
Dalteparin
An injectable blood thinner given under the skin to treat and prevent blood clots.
What is Dalteparin?
Dalteparin is a low-molecular-weight heparin (LMWH) that thins the blood to treat and prevent clots in the veins and lungs. It is given as a small injection under the skin. It is often used in hospital, in pregnancy, and to prevent clots in people with cancer.
Education and reference only. This is a plain-language guide to Dalteparin — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Dalteparin is an anticoagulant ('blood thinner') of the low-molecular-weight heparin family, supplied as a ready-to-use injection given just under the skin. It is a familiar routine choice for treating and preventing clots.
How it works
Dalteparin enhances a natural blood protein (antithrombin) that blocks clotting factors, especially factor Xa. This slows clot formation, stopping existing clots growing and reducing the chance of new ones.
Company & origin
Originated / developed by: Marketed by Pfizer..
Introduced in the 1990s as a low-molecular-weight heparin and used widely across the UK health service.
What it treats
Conditions Dalteparin is used for
Practical use
How to take Dalteparin
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Given as an injection just under the skin, usually into the fatty fold of the abdomen.
- Rotate injection sites and pinch a skin fold; do not rub afterwards.
- A nurse or pharmacist will teach you the technique if you self-inject.
- Take it at around the same time each day as prescribed.
- Do not stop without advice, as this can leave you at risk of clots.
- Report unusual bruising or bleeding to your team promptly.
Weighing it up
Advantages & disadvantages of Dalteparin
Advantages
- Reliable, predictable effect for treating and preventing clots.
- Usually no routine blood-level monitoring needed.
- Suitable for home self-injection, aiding earlier discharge.
- A trusted choice for clot prevention in people with cancer.
Disadvantages
- Requires an injection under the skin rather than a tablet.
- Bruising at injection sites is common.
- Needs caution and possible dose changes in kidney problems, pregnancy, and extremes of body weight.
- Carries a bleeding risk like all anticoagulants.
Practical use
Good to know
It is given as a quick injection under the skin, often into the tummy, and is frequently used for people with cancer who need ongoing clot prevention. Many people are taught to inject at home.
Who should not take it / use with caution
- People with active major bleeding or very high bleeding risk.
- Those with previous heparin-induced thrombocytopenia (low platelets due to heparin).
- People with severe uncontrolled high blood pressure or certain recent procedures (seek advice).
- Anyone allergic to dalteparin or other heparins.
- If you are due to have a spinal or epidural injection or a lumbar puncture, tell your team — the timing of these injections must be carefully managed to avoid bleeding around the spine (a rare but serious risk that can affect the nerves).
Monitoring
- Platelet count may be checked, particularly in the early treatment period.
- Closer monitoring (sometimes anti-Xa levels) in kidney problems, pregnancy, and very low or high body weight.
- Watch for any signs of bleeding during treatment.
Side effects
- Bruising, pain, or redness at the injection site.
- Bleeding or easy bruising elsewhere.
- A fall in platelet count (heparin-induced thrombocytopenia), uncommon but serious.
- Rarely, raised potassium or changes in liver blood tests.
Key interactions
- Other anticoagulants and antiplatelets (such as aspirin or clopidogrel) increase bleeding risk.
- NSAID painkillers add to bleeding risk.
- Share a full medicines list with your team, as some combinations need monitoring.
Available as: Pre-filled injection given under the skin.
Answers
Dalteparin: frequently asked questions
How is dalteparin given?
As a small injection just under the skin, usually into the tummy. Many people are shown how to inject it themselves at home.
Why might dalteparin be used in cancer?
It is a well-established option for preventing and treating clots in people with cancer, who are at higher clot risk. Your team will guide how long to continue.
Is bruising at the site normal?
Yes, bruising is common and usually harmless. Rotating sites and not rubbing the area can help reduce it.
Do I need blood tests on dalteparin?
Routine level testing is not usually required, but platelets and kidney function may be monitored, with closer checks in certain situations.
When should I seek help?
Contact your team urgently for bleeding that will not stop, blood in urine or stool, or heavy unexplained bruising.
The wider class
About Heparins
Dalteparin belongs to the heparins class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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