If you’re living with paroxysmal nocturnal hemoglobinuria (PNH), you may have experienced abdominal pain, possibly with bloating. Abdominal pain is a common PNH symptom, and about one-third of people report it when they receive a diagnosis of paroxysmal nocturnal hemoglobinuria.

Although abdominal pain is a common experience with this rare disease, it may also be a sign that you’re at higher risk of developing serious complications. It’s important to understand the potential causes of abdominal pain and bloating and when they may signal a medical emergency.

No matter what’s causing your abdominal pain, your doctor can help you pinpoint the cause and recommend treatment options to help you feel better.

How Does PNH Cause Abdominal Pain and Bloating?

Paroxysmal nocturnal hemoglobinuria could be connected to your abdominal pain and bloating for a few reasons. You and your doctor may need to work through several possibilities to determine which one is causing your pain so you can get effective treatment.

Muscle Spasms

When your body’s red blood cells break down (called hemolysis), they release hemoglobin into your bloodstream. The hemoglobin binds to nitric oxide, a chemical that usually relaxes your muscles. However, when too much of your nitric oxide is bound to hemoglobin, it can’t fulfill that role. You may then experience muscle spasms, or dystonia, throughout your body, including in and around your abdomen. This can cause what feels like abdominal cramping and pain, as well as gas buildup, which can lead to bloating.

Side Effects of PNH Treatment

Many of the treatments for PNH may cause abdominal pain as a side effect. For instance:

• About 10 percent of people taking ravulizumab-cwv (Ultomiris) report abdominal pain.
• Between 1 percent and 10 percent of people taking eculizumab (Soliris) experience gastrointestinal symptoms such as abdominal pain.
• Around 20 percent of people taking pegcetacoplan (Empaveli) experience abdominal pain.
• Between 8 percent and 15 percent report abdominal pain while taking iptacopan (Fabhalta).
• More than two participants experienced abdominal pain during clinical trials for crovalimab-akkz (PiaSky).

Other treatments may cause abdominal pain, too, so talk to your doctor if you begin experiencing it, especially if you’ve just started a new regimen.

Blood Clots

When you have PNH, you’re more likely to get blood clots in your veins, a condition known as thrombosis. Researchers know that 1 out of 3 people diagnosed with PNH get blood clots, and the number may actually be higher. It’s unknown why this condition seems to cause blood clots, but it may have to do with platelets sticking together or with the lack of nitric oxide in the blood.

A clot can develop in the abdominal blood vessels, among other sites in your body. If you get a blood clot in the blood vessels that supply intestines, the area may feel warm and painful and swell up. While this swelling can feel like bloating, it’s actually from an increase in fluid. You might also feel full or bloated, even when you haven’t eaten recently. Your pain may be sharp and difficult to ignore.

If you have sharp pain, feel warmth, or develop swelling in part of your abdomen and suspect a blood clot, get emergency medical care immediately. These blood clots can be life-threatening, and you need help right away.

Similarly, another type of blood clot called a pulmonary embolism occurs in the arteries between the heart and lungs. Symptoms include chest pain and shortness of breath.

Budd-Chiari Syndrome

You can also get a blood clot in the vein that goes out from your liver. This is called Budd-Chiari syndrome. Symptoms are similar to those of other abdominal blood clots, except you may not feel bloated or full because it’s not affecting your intestines. Your pain may also be closer to your liver, which is near the bottom of your rib cage, on your right side. If you have Budd-Chiari syndrome, you may also develop jaundice, in which your skin and the whites of your eyes appear yellowish.

Related Conditions

Sometimes conditions associated with PNH may cause abdominal pain and bloating.

Paroxysmal nocturnal hemoglobinuria may be connected to inflammatory bowel disease (IBD) — Crohn’s disease or ulcerative colitis. IBD involves chronic inflammation in the gastrointestinal tract. IBD can also cause abdominal pain, though most people will also experience other symptoms as well, like diarrhea, weight loss, or bloody stools.

Paroxysmal cold hemoglobinuria is a rare blood disorder that, like PNH, causes hemolysis of red cells, but it occurs when the body is exposed to cold temperatures. It’s extremely rare for this to occur alongside PNH, but it has happened at least once. Paroxysmal cold hemoglobinuria can also cause abdominal pain.

Other Common Causes of Abdominal Pain and Bloating

Just because you live with paroxysmal nocturnal hemoglobinuria doesn’t necessarily mean that it’s causing your abdominal pain and bloating. Other conditions can result in these symptoms.

Bloating may be caused by:

• Gas caught in your stomach
• Menstrual cycle or hormonal fluctuations
• Digestive problems
• Stomach inflammation
• Certain cancers

Bloating itself can cause abdominal pain, or it can occur with a wide variety of conditions, including:

• Appendicitis
• Diverticulitis
• Kidney infection
• Urinary tract infection
• Endometriosis
• Ovarian cysts
• Ulcers
• Gastrointestinal reflux disease
• Cancer

If you’re experiencing persistent abdominal pain, with or without bloating, get medical help. If the pain is severe, seek urgent care right away.

Managing Abdominal Pain and Bloating

If you and your doctor determine that your abdominal pain is caused by paroxysmal nocturnal hemoglobinuria, managing it involves finding an effective treatment that works for you.

Clinical trials are testing new ways to treat PNH. If you want to join one of these studies, talk to your hematology team. They should be able to connect you with researchers who can help you participate in this kind of testing.

Talk to Your Doctor

If you experience severe or worsening abdominal pain, get medical attention right away. Your health care provider will likely order tests to check for a blood clot or other complications. If you’re experiencing a blood clot, you’ll likely need to take an anticoagulant medication.

If your abdominal pain isn’t severe, but it persists or returns regularly, make a follow-up appointment with your doctor as soon as possible. They should be able to help you determine the source of your pain and get the treatment you need to improve your quality of life.

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.

Have you experienced abdominal pain and bloating with PNH? How have these symptoms affected your life? Share your experience in the comments below, or start a conversation by posting on your Activities page.