patients pi faqs What

What is PI?

PI stands for primary humoral immunodeficiency disease. There are more than 450 different kinds of PI.1  With PI, part of your immune system, which is what protects you from infections and fights off diseases, is missing or doesn't function properly. As a result, your body can't protect you from germs as well as it should, so you are more likely to develop infections and be sick more often. Learn more about PI.

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Hear Joanne, a PI patient and retired registered nurse, describe her journey to getting diagnosed with PI.



patients PI faqs what causes

What causes PI?

Primary immunodeficiency disorders occur when parts of the immune system (such as certain cells ​or antibodies) are either not working properly, too low, or missing altogether.1,2



patients pi faqs What are

What are symptoms of PI?

The signs and symptoms of PI vary from person to person. The most common symptoms include1,2:

  • Chronic, recurring infections that are more severe, longer lasting, and more difficult to cure, such as sinus infections, when compared to people with healthy immune systems
  • Frequently getting sick with infections, such as a common cold, that a healthy immune system would normally be able to fight off
  • Autoimmune problems, such as autoimmune lung or skin disease, which happen when the immune system attacks the body's own organs. Other issues include anemia, celiac disease, arthritis, lupus, and thyroid disorders2



patients pi faq Can I

Can I catch PI? Is PI contagious?

PI is not contagious; you can't catch it from someone else. PI is usually inherited, which means it is carried through the genes of your parents. If you have the disease, you might pass it along to your children, but you won't give it to anyone else.1,2



patients pi faq What medications

What medications are used to treat PI?

There are more than 450 types of primary immunodeficiency. For PI disorders that affect antibody production, doctors may recommend immune globulin replacement therapy.Over-the-counter drugs such as aspirin, decongestants, and/or expectorants are used to treat symptoms. Antibiotics are also used to treat infections and deal with a wide range of germs that have a greater impact on people with PI.2

Other treatments may also be available.2



patients pi faq What is IG

What is immune globulin (IG)?

IG stands for immune globulin. Immune globulin, or IG, is a medicine made from proteins from human plasma, taken from healthy donors, and contains purified antibodies. Plasma is the liquid part of the blood that contains antibodies needed to keep the body healthy.

Immune globulin is given to people with PI to replace missing or ineffective proteins to help the immune system protect against germs and other threats. It is sometimes referred to as IG replacement therapy.

Learn more about IG therapy and how to prepare for conversations with your healthcare team. Download the guide now.



patients What is the

What's the difference between subcutaneous IG therapy and intravenous IG therapy?

Subcutaneous immune globulin (SCIG) is administered under the skin while intravenous immune globulin (IVIG) therapy is administered through a vein. Different IG products have different concentrations. This means they may require more or less volume to be infused. XEMBIFY is an SCIG replacement treatment used to treat PI in patients 2 years of age and older.

Learn more about IG therapy and how to prepare for conversations with your healthcare team. Download the guide now.




What is XEMBIFY®?

XEMBIFY® (immune globulin subcutaneous human–klhw) is a 20% immune globulin used in the treatment of primary humoral immunodeficiency disease (PIDD) in patients 2 years of age and older. XEMBIFY is for subcutaneous administration only.

  • Thrombosis (formation of blood clots within blood vessels) may occur with immune globulin products, including XEMBIFY. Before you take XEMBIFY, talk to your doctor if you:
    • Are older
    • Are sedentary (need to lie down or sit down) for long periods of time
    • Are taking estrogen-containing medicines (birth control pills, hormone replacement therapy)
    • Have a permanent intravenous (IV) catheter
    • Have hyperviscosity of the blood (diseases such as multiple myeloma or other causes of elevated proteins in the blood)
    • Have cardiovascular (heart) problems or previous history of stroke
  • Thrombosis may occur even if you don't have any risk factors
  • If you are at risk of thrombosis, your doctor may prescribe XEMBIFY at the minimum dose and infusion rate. Make sure you drink plenty of fluid before taking XEMBIFY. Make sure your doctor is checking you regularly for signs and symptoms of thrombosis and is checking your blood viscosity if you are at risk of hyperviscosity
Who should not use XEMBIFY?
  • XEMBIFY should not be used if you have had a severe allergic reaction to human immune globulin, or if you have been told by a doctor that you are IgA deficient and have developed antibodies to IgA and hypersensitivity after exposure to a previous plasma product
What are possible serious side effects of XEMBIFY?
  • Hypersensitivity. Severe allergic reactions may occur with immune globulin products, including XEMBIFY. If you have a severe allergic reaction, stop the infusion immediately and get medical attention. XEMBIFY contains IgA. If you have known antibodies to IgA, you may have a greater risk of developing potentially severe allergic reactions
  • Aseptic meningitis syndrome (AMS). Aseptic meningitis is a non-infectious inflammation of the membranes that cover the brain. It causes a severe headache syndrome, which may occur with human immune globulin treatment, including XEMBIFY. If you are showing signs and symptoms of AMS, your doctor may conduct a thorough neurological evaluation including spinal tap (sampling fluid which surrounds the spinal cord) to rule out other causes of meningitis. Stopping human immune globulin treatment has resulted in the end of signs and symptoms within several days. Treatment may include analgesics (pain medicines) and/or a special procedure known as a "blood patch" to stop headache
  • Kidney problems or failure. Kidney problems or failure may occur with use of human immune globulin products, especially those containing sucrose (sugar). XEMBIFY does not contain sucrose. If you have kidney disease or diabetes with kidney involvement, your doctor should perform a blood test to assess your hydration level and kidney function before beginning immune globulin treatment and at appropriate intervals thereafter. If your doctor determines that kidney function is worsening, they may discontinue treatment
  • Hemolysis. Your doctor should monitor you for symptoms of hemolysis (destruction of red blood cells causing anemia, or low red blood cell count). If your doctor suspects hemolysis, they should perform additional tests to confirm
  • Transfusion-related acute lung injury (TRALI). TRALI is a rare but serious syndrome characterized by sudden acute respiratory distress following transfusion. If your doctor suspects TRALI, they will monitor you for any other lung issues. TRALI may be managed with oxygen therapy
  • Transmissible infectious agents. Because XEMBIFY is made from human blood, it may carry a risk of transmitting infectious agents such as viruses, the variant Creutzfeldt-Jakob disease (vCJD) agent, and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent. No cases of transmission of viral diseases or CJD have been associated with the use of XEMBIFY
  • Interference with lab tests. Because XEMBIFY contains a variety of antibodies, blood tests to determine antibody levels may be falsely elevated. Be sure to tell your doctor or lab technician that you are using XEMBIFY
What are other possible side effects of XEMBIFY?
  • In clinical studies of XEMBIFY, some patients experienced local side effects (at the injection site) including pain, redness, puffiness, bruising, nodules, itching, firmness, scabbing and swelling at the site on the skin where the injection occurred. Some patients experienced non-injection-site side effects including cough and diarrhea.
  • Use of XEMBIFY may interfere with the immune response to virus vaccines, such as vaccines for measles, mumps, rubella and varicella. Tell your doctor you are taking XEMBIFY before getting vaccinations

Please see full Prescribing Information for XEMBIFY.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call 1-800-FDA-1088.


Patients Pi FAQs References


  1. What is PI? Immune Deficiency Foundation website. Accessed January 31, 2024.
  2. Ballow M, Epland K, Heimall J, et al, eds. Immune Deficiency Foundation Patient & Family Handbook for Primary Immunodeficiency Diseases. 6th ed. Towson, MD: Immune Deficiency Foundation; 2019.



PI, primary humoral immunodeficiency disease

SCIG, subcutaneous immune globulin