Thrombosis (blood clotting) is a major risk for people living with paroxysmal nocturnal hemoglobinuria (PNH). As many as 1 out of 3 people with this rare disease may experience a blood clot, which can be life-threatening.

If you have PNH, your doctor may recommend taking anticoagulants (blood thinners). Anticoagulants can help treat thrombotic events. A thrombotic event is when a blood clot forms within a blood vessel, which can obstruct blood flow to vital organs and tissues.

Understanding anticoagulants can help you stay safe and improve your quality of life while living with PNH. Here are some facts to keep in mind when using these medications.

1. You May Only Need To Take Anticoagulants for a Short Time

Your doctor may recommend taking anticoagulants if they think you are at risk of thrombosis. For example, you may need this medication if you have had blood clots in the past. However, anticoagulants may simply be a temporary solution until your PNH is better controlled. You may be able to stop taking anticoagulants if you start other PNH medications that work well to minimize symptoms.

Make sure to talk to your doctor before you stop taking a drug, as this could affect your health. You may need to take anticoagulants over the long term to avoid major PNH-related problems.

2. It May Take Time To Find the Right Dosage

For one type of anticoagulant, warfarin (Coumadin), the proper dose may not be clear right away. Your doctor may start you out on one dosage and then perform blood tests to look at how quickly your blood is clotting. If the clotting process happens too fast or too slow, your doctor may modify your dose.

Newer types of anticoagulants don’t require this process. Your doctor may recommend follow-up visits to ask you about potential side effects, but you won’t usually need to undergo regular blood tests to use these medications.

3. Seek Emergency Medical Care if You Think You Have a Blood Clot

Blood clotting problems can be life-threatening for those with PNH. Blood clots can form in locations like the liver or a limb. They may also develop in one location and then travel throughout the body until they create a thromboembolism (blockage of blood flow in a different part of the body).

Learn to recognize the signs of a potential blood clot. They may include:

• Sudden abdominal pain, swelling, and warmth
• Signs of a stroke, including extreme headache, sudden speech or vision problems, facial drooping, or numbness or weakness that affects only one side of your body
• Redness, swelling, and pain in a particular area of your skin
• Cramping pain, soreness, swelling, and warmth in an arm or leg
• Sharp chest pain, difficulty taking a deep breath, coughing up blood, feeling lightheaded, anxiety, or sweating an unusual amount

Seek immediate medical attention if you notice any of the symptoms above. Getting help right away can protect your health.

4. Anticoagulants Can Cause Bleeding Problems

Anticoagulants help keep your blood from clotting. However, this may pose a problem when you actually need your blood to form a clot, such as after an injury. Anticoagulants may lead to an increased risk of unusual bleeding, especially for people with PNH who have low levels of platelets (cell fragments that help form blood clots).

Thrombocytopenia (low platelet counts) may lead to symptoms like:

• Frequent nosebleeds
• Bleeding gums
• More bleeding than expected from a small injury
• Petechiae (tiny red or purple bumps on your skin)
• Heavy menstrual periods
• Repeated bruising

If you’re experiencing any of these issues, inform your doctor. You may need to adjust your dose of anticoagulants to find a good balance between avoiding blood clots and preventing severe bleeding.

5. Certain Foods May Increase Your Risk of Clots or Bleeding

Although you don’t need to follow a special diet while taking anticoagulants, certain foods and drinks may interfere with these medications.

Vitamin K can make warfarin less effective. Experts from Mayo Clinic recommend 120 micrograms of vitamin K per day for men and 90 micrograms for women — but too much may increase your risk of blood clots. Try to eat the same amount of vitamin K per day while on anticoagulants like warfarin. Be consistent when eating foods high in vitamin K, including:

• Green leafy vegetables like kale, spinach, and collard greens
• Other green vegetables like broccoli, brussels sprouts, and asparagus
• Soy-containing foods, including soybeans, edamame, and natto (a traditional Japanese food made from whole soybeans)
• Carrots and carrot juice
• Pumpkin
• Blueberries

Other foods can have the opposite effect, further preventing clotting and potentially causing bleeding problems. While on anticoagulants, limit your intake of foods or supplements that contain grapefruit, garlic, ginger, cayenne, turmeric, or ginkgo biloba.

6. You May Need To Take Precautions Before and After Surgery

If you have PNH and are on anticoagulants, surgery may be risky. This includes major surgeries as well as minor outpatient or dental procedures. Surgery may cause bleeding and clotting problems.

If you need surgery, your doctor may have you stop taking anticoagulants, use a different dose, or switch to a different type of anticoagulant. The best approach may depend on what type of procedure you are having and your risk of a blood clot or abnormal bleeding.

7. It’s a Good Idea To Wear Medical Alert Jewelry

Experts recommend wearing a medical alert bracelet that states that you’re taking anticoagulants. This information can be helpful if you need immediate medical care after an accident or injury. It may also help a surgeon minimize health risks if you need emergency surgery and don’t have time to talk to your health care team about your condition.

8. You Can Take Birth Control Pills With Anticoagulants

In general, you can keep taking birth control medications while using anticoagulants if you have not yet gone through menopause. Studies have shown that combining these medications won’t make birth control less effective.

Some anticoagulants have been known to cause pregnancy complications, and so does having PNH. It’s important to discuss your family planning intentions with your doctor. They can explain the risk factors and make sure your medications are appropriate, whether you are trying to avoid or achieve a pregnancy.

9. Taking the Right Anticoagulants Is Important During Pregnancy

Pregnancy can be risky for both you and your baby if you have PNH. It’s important to have regular visits with specialists while pregnant, including a PNH specialist and a maternal-fetal medicine specialist (doctor who specializes in high-risk births).

Your risk of experiencing a blood clot increases when you are pregnant. Therefore, doctors typically recommend using anticoagulants during this time. However, not all anticoagulants are safe to take during pregnancy. For example, warfarin can cause birth defects, developmental delays, and seizures in a developing baby. Always consult your doctor if you become pregnant or are thinking about having a child.

10. Current Treatments Make Blood Clotting Problems Less Likely

Anticoagulants help treat PNH symptoms, but they don’t address the underlying causes of the disease. This type of treatment is known as supportive therapy. In addition to supportive therapy, you will also need medications that help prevent intravascular hemolysis — a condition that occurs when your complement system (part of your immune system) attacks your red blood cells. Medications that block this process, called complement inhibitors, include eculizumab (Soliris), ravulizumab (Ultomiris), and iptacopan (which is currently in clinical trials).

Complement inhibition lessens the risk of PNH-related problems like blood clots. One study found that a person’s risk of blood clots dropped by 85 percent after they started taking eculizumab.

Finding a PNH treatment plan that successfully keeps your condition under control may lessen your need for supportive therapies like anticoagulants. However, make sure to take anticoagulants if your doctor recommends them — it’s still possible to experience blood clots while using complement inhibitors.

Talk With Others Who Understand

On myPNHteam, the social network for people with paroxysmal nocturnal hemoglobinuria and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with PNH.

Are you taking anticoagulants for PNH? Share your experience in the comments below, or start a conversation by posting on your Activities page.