Q: I’ve been told I need a blood thinner. What do I need to know about them?

A: Blood thinners, or anticoagulants, are a life-saving medication taken by millions of Americans every day. Your doctor may prescribe this medication to prevent blood clots in the heart, lungs, or brain. It can also help slow the recurrence of any previous blood clots that led to pulmonary embolism, deep vein thrombosis, or stroke.

Blood thinners come in different forms including oral or injectable. The oldest blood thinner to take by mouth is well-known warfarin (Coumadin). Now, newer generations of blood thinners commonly known as direct oral anticoagulants (DOACs) have taken over as standard of care for most of the medical conditions where warfarin was used.

For patients who take warfarin, it is very important that your drug levels are maintained in a strict range. Not enough blood thinner in your body could mean the medication isn’t working properly, while too much could increase your bleeding risk. Newer DOACs have the advantage that such monitoring is not required.

They are safer than Coumadin in terms of bleeding risk and extremely effective. They include such medications as dabigatran (Pradaxa), rivaroxaban (Xarelto), edoxaban (Savaysa), and apixaban (Eliquis). DOACs are taken by mouth once or twice a day. It is generally recommended that you take DOACs at the same time of day.

Patient criteria for DOACs vary, based on the type of medical condition diagnosed. If you had a blood clot because of pregnancy or need to have a procedure, your doctor may prescribe a switch from oral agents to injectable blood thinners. DOACs are not studied or recommended for pregnant patients and for patients with antiphospholipid antibody syndrome. In patients with cancer-associated clots, DOACs can now potentially be used, though some clinicians may still prefer injectable forms.

While on any type of blood thinner, avoid activities that have a significant risk of injury that causes bleeding. Contact your health-care provider right away if you have any signs of internal bleeding such as:

  • Black stool

  • Nose bleeds

  • Heavy menstrual periods

  • An expanding bruise

  • A very severe headache

Depending on your blood clot risk, your doctor may recommend blood thinner treatment for a few months or indefinitely. Always take your blood thinner as prescribed and do not skip doses. Stopping a blood thinner on your own can lead to a serious blood clot. If you are concerned about your treatment, talk to your health-care provider.

Parth M. Rali is an associate professor in the division of thoracic medicine and surgery at Lewis Katz School of Medicine at Temple University and the director of Temple University Health System’s Pulmonary Embolism Response Team (PERT) Program.