IVIg to SCIg: Considerations When Switching Immunoglobulin Therapies for Primary Immunodeficiency

For people living with primary immunodeficiency (PI), immunoglobulin replacement therapy (Ig) is a cornerstone of treatment. It helps prevent serious infections, reduces hospitalizations, and supports long-term health.

The immunoglobulin used in treatment comes from donated human plasma, and it can be administered in two different ways: through an intravenous infusion (IVIg), typically at a hospital or infusion center, although some people get IVIg at home, or through subcutaneous infusions (SCIg) that are usually done at home.

Once stable and therapeutic antibody levels are reached, the outcomes are similar, says Vincent Tubiolo, MD, an allergy, asthma, and immunology specialist in Santa Barbara, California.

“The main reasons most patients switch from IVIg to SCIg is related to cost, convenience, and side effects,” says Dr. Tubiolo.

The decision is a personal choice that works best when made through shared decision-making with your healthcare team. Here’s what you need to know.

One of the biggest shifts when moving from IVIg to SCIg is the level of personal responsibility involved. “When patients switch from IVIg to SCIg, the most intimidating process is the reality of administering your own infusion,” says Rekha Raveendran, MD, an allergist-immunologist at the Ohio State University Wexner Medical Center in Columbus.

With IVIg, infusions are administered by healthcare professionals in a medical setting, whereas SCIg is self-administered at home after training.

While many people appreciate the flexibility of home treatment, it also means taking responsibility for setting up infusions, monitoring reactions, and keeping supplies organized.

To help patients feel more comfortable with this option, nursing staff comes to the patient’s house to teach them how to infuse, says Dr. Raveendran.

“They typically receive one-on-one training provided through the specialty pharmacy, with nursing staff coming to the patient’s home to help teach them and troubleshoot issues. They typically will have at least three visits before they are expected to do their own infusions,” she says.

For some people, this level of involvement feels empowering, but for others, it can feel overwhelming. That’s why it’s important to talk through concerns with your healthcare provider before making the switch.

Side effects are a common reason people consider changing how they receive immunoglobulin therapy.

IVIg is more often associated with systemic side effects, such as headaches, fatigue, fever, chills, nausea, or flulike symptoms, says Raveendran. “Rarely, side effects can even include aseptic meningitis,” she says.

“Pretreatment with steroids, fluids, and antihistamines can help, but some patients are unable to tolerate IVIg even with these measures,” says Raveendran.

SCIg generally causes fewer systemic side effects, but local reactions at infusion sites are common, and include redness, swelling, itching, burning, or bruising. “Numbing creams can help make the infusions more tolerable,” she says.

IVIg is most often given every three to four weeks, with each infusion lasting three to four hours, and requires traveling to an infusion center or hospital.

“Patients who do not have time to spend several hours in an infusion center will often prefer to be able to infuse on their own time in the comfort of their own home,” says Raveendran.

A key difference between IVIg and SCIg is how the medication enters the body. IVIg requires access to a vein, which can be easy for some people but challenging for others. Repeated needle sticks may become uncomfortable over time, especially for those with fragile veins or a long history of infusions. In some cases, a central line or port may be needed, which carries added risks such as infection or blood clots.

SCIg avoids the veins altogether because the medication is delivered just under the skin using small needles, most often in the abdomen, thighs, or upper arms.

Cost and insurance coverage play a major role in treatment decisions for most people, says Tubiolo.

IVIg administered in a hospital or infusion center is typically billed under the medical benefit and may include facility and administration fees. SCIg is often billed under the pharmacy benefit and shipped directly to the home, which can reduce some administration costs.

Quality of life is one of the most commonly cited reasons people consider switching from IVIg to SCIg.

But that’s not true for everyone. Some people prefer the structure and reassurance of clinic-based IVIg, especially if they feel anxious about self-infusion.

Tubiolo “strongly recommends” SCIg for people who are able to choose it. There are exceptions, such as very ill people who don’t have the ability to self-administer the SC form of the drug and don’t have resources for someone else to assist, and people with bleeding problems, including easy bruising from the subcutaneous injections.

• Both IVIg and SCIg effectively replace missing antibodies in people with primary immunodeficiency, and outcomes are similar once stable IgG levels are reached.
• The choice between IVIg and SCIg often depends on lifestyle factors such as comfort with self-infusion, scheduling flexibility, vein access, side effects, and insurance coverage.
• IVIg is more likely to cause systemic side effects like headaches or flulike symptoms, while SCIg more commonly causes mild skin reactions that often improve over time.
• Because SCIg requires more hands-on involvement and IVIg carries rare but serious risks related to IV access, decisions are best made with your healthcare team.