What is immunoglobulin injection?

October 5, 2025 •

4 min read

Immunoglobulin therapy is a powerful treatment derived from the pooled blood plasma of thousands of healthy donors. These concentrated doses of antibodies, known as an immunoglobulin injection, are used to boost a weakened immune system or help modulate an overactive one in people with certain conditions.

Quick Summary

Immunoglobulin therapy is an infusion of donor-derived antibodies to help those with compromised immune systems. It treats immune deficiencies and autoimmune disorders via intravenous (IVIG) or subcutaneous (SCIG) administration, providing essential antibodies to protect against infection and regulate immune response.

Key Points

Source of Antibodies: Immunoglobulin injections are made from the pooled blood plasma of thousands of healthy donors.
Immune Function: The therapy provides or modulates antibodies to help fight infections and regulate the immune system.
Key Uses: Treats primary immune deficiencies, autoimmune disorders like lupus and CIDP, and some neurological diseases.
Administration Routes: Two main types are intravenous (IVIG) for higher, less frequent doses, and subcutaneous (SCIG) for smaller, more frequent doses.
Side Effects: Mild side effects like headache and fever are common, but serious side effects such as blood clots are rare.
Treatment Location: IVIG is typically administered in a clinical setting, while SCIG allows for greater flexibility and can be self-administered at home.
Long-term Therapy: Many patients require ongoing immunoglobulin therapy to maintain protective antibody levels, which typically last about 3 to 4 weeks.

What is an immunoglobulin injection?

An immunoglobulin injection is a medical treatment that delivers concentrated antibodies, or immunoglobulins, into a person's body. Immunoglobulins are a vital component of the immune system, produced by plasma cells to identify and neutralize foreign objects like bacteria and viruses. The product used for therapy is manufactured from the pooled blood plasma of thousands of healthy donors, ensuring a diverse range of antibodies. This makes it an invaluable treatment for individuals whose bodies either don't produce enough of their own antibodies or produce autoantibodies that attack healthy tissue.

How does it work?

Immunoglobulin therapy functions in two primary ways, depending on the condition it is treating:

Immune System Boost: For patients with primary immune deficiencies, the treatment replenishes their low antibody levels, giving their immune system the tools it needs to fight off infections.
Immune System Modulation: In autoimmune diseases, the immune system mistakenly attacks the body's own cells. High doses of immunoglobulin can help regulate this overactive immune response by blocking the damaging autoantibodies and reducing inflammation.

Conditions treated with immunoglobulin therapy

Immunoglobulin injections are prescribed for a wide array of conditions, ranging from primary immune disorders to autoimmune and inflammatory diseases. Key examples include:

Primary Immunodeficiencies (PI): Conditions like X-linked agammaglobulinemia or common variable immunodeficiency (CVID), where the body lacks the ability to produce sufficient antibodies.
Autoimmune Disorders: Includes chronic inflammatory demyelinating polyneuropathy (CIDP), lupus, myositis (dermatomyositis and polymyositis), and systemic vasculitis.
Neurological Diseases: Treatment for Guillain-Barré syndrome, multifocal motor neuropathy, and myasthenia gravis.
Hematological Conditions: Used for idiopathic thrombocytopenic purpura (ITP), where the immune system attacks and destroys platelets.
Kawasaki Disease: An inflammatory disease affecting children that can lead to heart complications if not treated.

Types of immunoglobulin injections: IVIG vs. SCIG

Immunoglobulin therapy is most commonly administered via two methods: intravenous (IVIG) or subcutaneous (SCIG). Your healthcare provider will determine the best option based on your condition, dose requirements, and lifestyle preferences.

Intravenous Immunoglobulin (IVIG)

IVIG is given directly into a vein, typically at a hospital or infusion center. The infusions are administered every three to four weeks, with each session lasting several hours. This route delivers a high dose of antibodies at once, resulting in a rapid, high peak of immunoglobulin in the bloodstream. While effective, the high dose can lead to more pronounced systemic side effects.

Subcutaneous Immunoglobulin (SCIG)

SCIG is infused just under the skin, usually in the abdomen or thighs, using a small needle. It involves smaller, more frequent doses—often weekly or biweekly—and can be done at home by the patient after proper training. The gradual absorption leads to more stable immunoglobulin levels and fewer systemic side effects, though local site reactions like swelling or redness can occur. Some patients find this greater flexibility improves their quality of life.


Feature	IVIG (Intravenous)	SCIG (Subcutaneous)
Administration	Into a vein	Under the skin (fatty tissue)
Frequency	Every 3-4 weeks	Weekly or biweekly
Location	Infusion center or hospital (can be home-based)	Usually at home
Infusion Time	Several hours	30-60 minutes
Antibody Levels	High initial peak, followed by gradual decline	Consistent, stable levels
Systemic Side Effects	More common (headaches, fever)	Less common
Local Side Effects	None	Common (swelling, redness at injection site)
Autonomy/Flexibility	Less flexible due to scheduled appointments	Highly flexible, self-administered

Risks and side effects

Most patients tolerate immunoglobulin injections well, but side effects can occur. These can be classified as minor and major.

Common and minor side effects

Headaches, chills, and fever
Muscle or joint aches
Nausea and fatigue
Redness, swelling, or itching at the injection site (more common with SCIG)

Rare and serious side effects

Aseptic Meningitis: Inflammation of the membranes covering the brain and spinal cord.
Thrombosis: Formation of blood clots.
Kidney Problems: Acute renal failure can occur, especially in patients with pre-existing kidney issues or high-dose therapy.
Severe Allergic Reaction (Anaphylaxis): A life-threatening reaction requiring immediate medical attention.

Conclusion

An immunoglobulin injection is a critical and versatile treatment that can dramatically improve the quality of life for individuals with compromised immune function or autoimmune diseases. By replacing a lack of functional antibodies or modulating an overactive immune response, this therapy helps the body defend against pathogens and reduce disease symptoms. While there are potential side effects, careful medical supervision and an understanding of the available administration routes, such as IVIG and SCIG, allow for personalized and effective treatment. Patients can discuss their lifestyle needs and medical requirements with their healthcare team to determine the optimal approach for managing their condition.

For more detailed information on specific conditions treated with immunoglobulin therapy, patients should consult their healthcare provider or reference authoritative sources like the Cleveland Clinic.

Frequently Asked Questions

The primary difference lies in the administration method. IVIG is given directly into a vein every 3-4 weeks, while SCIG is infused under the skin more frequently, often weekly.

Patients with weakened immune systems due to conditions like primary immune deficiencies, autoimmune diseases (such as lupus, myositis), or certain neurological disorders (like CIDP and Guillain-Barré syndrome) may require an immunoglobulin injection.

The frequency depends on the condition and administration method. IVIG is typically given every 3-4 weeks, while SCIG is usually given weekly or biweekly.

Common side effects of IVIG include headaches, flu-like symptoms, fever, chills, nausea, and fatigue. Taking pre-medications and staying hydrated can help reduce these symptoms.

Yes, SCIG is often self-administered at home after receiving proper training from a healthcare provider. This offers patients more flexibility and autonomy over their treatment schedule.

Yes, immunoglobulin therapy is generally considered safe and effective. Serious adverse events are rare due to the careful screening and processing of donated plasma. Patients are monitored for potential side effects, and risks are weighed against benefits by a healthcare provider.

Preparation can involve staying well-hydrated, especially for IVIG, and sometimes taking pre-medication as prescribed by your doctor. It is also recommended to bring a book or other activity, as infusions can take several hours.

The antibodies are harvested from the blood plasma of thousands of healthy, screened donors. This plasma is then processed and purified to create the final, concentrated product.