Blood Thinners: Uses, Side Effects, and Drug Interactions

How we reviewed this article: · Healthline

Blood thinners may be taken via mouth, vein, or skin to prevent blood clots, which might cause a heart attack or stroke. But, they may have serious side effects, especially if taken with other medications.

Blood clots can stop blood flow to the heart, lungs, or brain and can create a life-threatening situation. To prevent this, you may need to take blood-thinning medications.

It’s important to take them exactly as directed. When you don’t take enough, the medication won’t be as effective. Taking too much can lead to severe bleeding.

Read on to learn about how they work, who should take them, what side effects may occur, and any natural remedies you can also use.

Some medications work by interfering with your body’s ability to clot blood and slowing the time it takes for blood to clot. Others work by preventing cells (specifically

platelets

) from gathering and forming clumps. These are known as

anticoagulant and antiplatelet drugs

, respectively.

“Coagulate” is a medical term that means “to clot.” These blood thinners prevent blood clots by

increasing

the amount of time it takes your blood to clot.

Anticoagulants prevent clots from forming. Common anticoagulant blood thinners include:

warfarin

(Coumadin, Jantoven)

enoxaparin

(Lovenox)

heparin

Newer anticoagulants with less chance of bleeding complications include:

dabigatran (Pradaxa)

apixaban

(Eliquis)

rivaroxaban

(Xarelto)

On the other hand, antiplatelet drugs

prevent

blood cells (called platelets) from clumping together and forming clots. Examples of antiplatelet drugs are:

aspirin

clopidogrel (

Plavix

)

dipyridamole (Persantine)

prasugrel (Effient)

Taking antiplatelets and anticoagulants together can increase your risk of bleeding, however, depending on your medical conditions you may need to take a combination of these medications.

Your doctor will discuss the risks and benefits with you and determine which medications are best for you. If you are on warfarin, your doctor will also carefully monitor your dosage and may occasionally run a

prothrombin time (PT)

test. This blood test

measures

your international normalized ratio (INR).

INR is the rate at which your blood clots. An appropriate INR rate varies from person to person according to their medical history. Staying within your INR range can prevent you from bleeding excessively or clotting too easily.

Both anticoagulant and anti-platelet drugs are used to prevent a blood clot from forming.

What conditions blood thinners treat

Doctors often prescribe anticoagulants to people who have been diagnosed with some form of heart disease. Conditions or situations that may require the use of these medications include:

atrial fibrillation

(an irregular heart rhythm) to reduce the risk of

stroke

caused by blood clots forming in the heart and traveling to the brain

mechanical heart valves

, to prevent blood clots from forming on the valve surfaces, which can lead to valve malfunction or stroke

as a preventive measure in people at high risk of stroke

following surgery, especially joint replacements

peripheral artery disease (PAD)

in combination with certain other conditions to reduce the risk of blood clots forming in narrowed arteries

coronary artery disease (CAD)

in combination with certain

other conditions

like atrial fibrillation to prevent blood clots and reduce the risk of heart attack

Another class of medications called thrombolytics

may be used

to dissolve a blood clot that has already formed, such as in the case of

deep vein thrombosis (DVT)

or

pulmonary embolism

, for example. The way these drugs work is also referred to as fibrinolytic therapy.

Blood thinners may cause side effects in some people. Excessive bleeding is the

most common

reaction. It can occur in a variety of ways, including:

heavy periods

bloody or discolored urine or feces

nosebleeds

bleeding gums

prolonged bleeding from a cut

bruising easily

Other side effects can include:

dizziness

muscle weakness

hair loss

rashes

The presence of blood thinners in your system can increase your chance of internal bleeding after an injury. Go to the hospital immediately if you experience any of these side effects after falling or bumping your head — even if you don’t have external bleeding.

Your doctor may tell you to limit your participation in contact sports to reduce the chance of bleeding. However, this doesn’t mean you can’t exercise or live your day-to-day life.

Swimming, walking, and jogging are excellent forms of exercise and are safe for most people taking anticoagulants. Discuss with your doctor which types of exercise may be best for you.

Tell your dentist you’re taking blood thinners to avoid excessive bleeding during regular teeth cleanings. It’s also important to protect yourself when using knives, scissors, or yard equipment.

Thrombolytics

can also cause

excessive bleeding from the administration site, or spontaneous bleeding in the area where the clot is sitting. Potential complications can include:

blood in the urine or stool

nosebleed

abnormally heavy or unusual vaginal bleeding

stroke

The blood clot may also break into pieces. The pieces may then infrequently travel to other body parts and cause more problems.

Various foods, herbs, and medications can interfere with blood thinners. These substances can make the drug more or less effective than your dosage would suggest.

However, not all blood thinners are affected by the same substances. It’s important to speak with your doctor or cardiologist about your diet and how it may impact the effectiveness of your medication.

Vitamin K

Vitamin K

can lessen

the effectiveness of some anticoagulants, such as

warfarin

. You can continue to eat the foods your normally eat but if you are planning to make major changes than contact your doctor first. The following foods, if consumed in a different quantity than usual, may affect your level:

cabbage

brussels sprouts

broccoli

asparagus

endive

kale

lettuce

spinach

mustard greens

turnip greens

collard greens

Herbs

People who take anticoagulant medications should use herbal supplements and teas with caution. Several herbs interfere with the anticlotting abilities of blood thinners. They can also increase your risk of bleeding and the amount of time you bleed.

Speak with your doctor before using any herbal supplement or tea, especially the following:

chamomile

echinacea

clove

evening primrose oil

dong quai

licorice

ginseng

gingko biloba

goldenseal

willow bark

Alcoholic beverages and cranberry juice can contribute to the development of side effects when using blood thinners. Avoid these items as much as possible.

Medications

Take prescription and over-the-counter medications with caution when you’re using blood thinners. Many medications can increase your chance of bleeding excessively if you take them with blood thinning medications.

Several antibiotics, antifungal drugs, blood pressure medications, and antidepressants

can increase

your chance of bleeding. This also includes

nonsteroidal anti-inflammatory drugs (NSAIDs)

like Ibuprofen (Advil, Motrin) or Naproxen (Aleve). Make sure to tell your doctor about all the medications you’re taking.

Taking over-the-counter bismuth subsalicylate (

Pepto Bismol

and others) can also

increase

bleeding with blood thinners because it falls into the same medication category as aspirin.

In addition, taking certain thrombolytic medications with

ACE inhibitors

may

increase

your chance of developing

angioedema

, or swelling. Combining these drugs with antiplatelet or anticoagulant drugs

may also increase

your bleeding chance.

Many of the herbs that may interact with blood-thinning medications do so because they, too,

have either

antiplatelet or anticoagulant properties.

Check with your doctor before eating these foods if you’re taking a blood-thinning medication because they could thin your blood too much and increase your risk of bleeding.

In addition, foods rich in vitamin E are natural blood thinners. Several oils

contain

vitamin E, such as olive, corn, soybean, and wheat germ. Other food sources of vitamin E include:

spinach

tomatoes

mangoes

kiwis

peanut butter

almonds

sunflower seeds

broccoli

Natural anticoagulants may also benefit your heart health, but more research is needed to verify their benefits and safety. Take them with caution if you are already on anticoagulants or antiplatelets.

Blood clots can be dangerous because they interfere with blood flow to your vital organs. If you have issues with your heart, you may have a greater chance of developing blood clots and may need to take blood-thinning medications.

These drugs work by either thinning your blood or increasing the time it takes for blood clots to form. However, they may have some side effects.

It’s important to discuss your diet, lifestyle activities and other medications you take with a doctor prior to taking them and if other major changes happen after your start treatment. It’s also important to take these medications exactly as your doctor instructs.