Taking tetracycline together with dalteparin sodium may make dalteparin work less well as a blood thinner. That means it may protect you less against blood clots. If you need both medicines, tell your doctor or pharmacist so they can keep an eye on you and decide whether anything needs to change. Don't stop or adjust either medicine on your own.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.