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Generic name: dalteparinDAL-te-PAR-in ]
Drug class: Heparins

Medically reviewed by Sophia Entringer, PharmD. Last updated on Dec 27, 2023.

What is Fragmin?

Fragmin is an anticoagulant that helps prevent the formation of blood clots.

Fragmin is used together with aspirin to prevent blood vessel complications in people with certain types of angina (chest pain) or heart attack.

Fragmin is used to prevent a type of blood clot called deep vein thrombosis (DVT), which can lead to blood clots in the lungs (pulmonary embolism). A DVT can occur after certain types of surgery, or in people who are bed-ridden due to a prolonged illness.

Fragmin is used long-term to treat a type of blood clot called venous thromboembolism (VTE) in people with cancer.

Fragmin is also used reduce the recurrence of venous thromboembolism (VTE) in children one month of age and older.

Fragmin may also be used for purposes not listed in this medication guide.


You should not use Fragmin if you have active bleeding, or a low level of platelets in your blood after testing positive for a certain antibody while using Fragmin.

Also if you are undergoing epidural/neuraxial anesthesia do not use Fragmin to treat unstable angina or non-Q-wave myocardial infarctions (heart attack).

Fragmin can cause a very serious blood clot around your spinal cord if you undergo a spinal tap or receive spinal anesthesia (epidural), especially if you have a genetic spinal defect, a history of spinal surgery or repeated spinal taps, or if you are using other drugs that can affect blood clotting, including blood thinners or NSAIDs (ibuprofen, Advil, Aleve, and others). This type of blood clot can lead to long-term or permanent paralysis.

Get emergency medical help if you have symptoms of a spinal cord blood clot such as back pain, numbness or muscle weakness in your lower body, or loss of bladder or bowel control.

Before taking this medicine

You should not use Fragmin if you are allergic to dalteparin, heparin, or pork products, or if you have:

Fragmin may cause you to bleed more easily, especially if you have:

Fragmin can cause a very serious blood clot around your spinal cord if you undergo a spinal tap or receive spinal anesthesia (epidural). This type of blood clot could cause long-term or permanent paralysis, and may be more likely to occur if:

To make sure Fragmin is safe for you, tell your doctor if you have ever had:

It is not known whether Fragmin will harm an unborn baby. However, some forms of this medicine contain a preservative that may be harmful to a newborn. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It may not be safe to breastfeed while using dalteparin. Ask your doctor about any risk.

How should I use Fragmin?

Use Fragmin exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

When used for DVT or blood vessel complications, Fragmin is usually given every day until the clotting condition improves. When used for VTE, Fragmin is often used for several months.

Fragmin is injected under the skin. A healthcare provider may teach you how to properly use the medication by yourself.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you don't understand all instructions.

Prepare an injection only when you are ready to give it. Do not use if the medicine has changed colors or has particles in it. Call your pharmacist for new medicine.

Your healthcare provider will show you where to on your body to inject Fragmin. Use a different place each time you give an injection. Do not inject into the same place two times in a row.

You should be sitting or lying down during the injection. Do not inject Fragmin into a muscle.

Do not mix Fragmin with other medications in the same syringe unless your doctor tells you to.

If you use a single-dose prefilled syringe, follow the injection instructions closely. Single-dose syringes come in two different types and the directions for use are not the same for each type.

If you need surgery or dental work, tell your surgeon or dentist you currently use dalteparin. If you need anesthesia for a medical procedure or surgery, you may need to stop using dalteparin for a short time.

You will need frequent medical tests.

Store at room temperature away from moisture and heat.

Once you have used a Fragmin vial (bottle) for the first time, you may use that vial for up to 2 weeks. Throw the vial away after 2 weeks, even if there is still medicine left inside.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time.Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Overdose may cause excessive bleeding.

What should I avoid while using Fragmin?

Avoid taking aspirin unless your doctor recommends it as part of your treatment. Aspirin can increase your risk of bleeding.

Avoid activities that may increase your risk of bleeding or injury. Use extra care to prevent bleeding while shaving or brushing your teeth.

Fragmin side effects

Get emergency medical help if you have any signs of an allergic reaction to Fragmin: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Also seek emergency medical attention if you have symptoms of a spinal blood clot: back pain, numbness or muscle weakness in your lower body, or loss of bladder or bowel control.

Stop using Fragmin and call your doctor at once if you have:

Common Fragmin side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Fragmin?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with Fragmin, especially other medicines used to treat or prevent blood clots, such as:

This list is not complete. Other drugs may interact with dalteparin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Fragmin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.