Dalteparin comes as as a solution (liquid) in vials and prefilled syringes to inject subcutaneously (under the skin). It is usually given once a day, but may be given twice a day for certain conditions. The length of your treatment depends on the condition that you have and how well your body responds to the medication. If you are using dalteparin to prevent DVT after surgery, it is usually given for 5 to 10 days or sometimes for up to about 1 month. If you are using dalteparin is used to prevent DVT in people who are on bedrest, you will receive the medication for 12 to 14 days. If you have cancer and dalteparin is used to treat and prevent DVT, you may need to use the medication for up to 6 months.