IVIG (intravenous immunoglobulin) causes side effects in a significant number of patients, ranging from mild reactions during the infusion to rare but serious complications. Headache is the most common, affecting up to one-third of patients over the course of their treatment. Most side effects are manageable and resolve on their own, but a few deserve serious attention.
Common Infusion Reactions
The most frequent side effects happen during or shortly after the infusion itself. In a survey of roughly 1,500 patients with primary immunodeficiency receiving IVIG, 28% reported headache at least once, 19% reported fever, and 14% reported nausea. Chills are also common, though reported less consistently. On a per-infusion basis, headache shows up in about 5% to 20% of individual treatments.
These reactions tend to be worse during the first few infusions and often improve over time as your body adjusts. They’re also closely tied to how fast the infusion runs. Infusion centers typically start at a slow rate and increase it in steps every 30 minutes, only moving faster if you’re tolerating it well. Rates above about 3 mL/kg per hour are associated with more frequent reactions. If symptoms flare up mid-infusion, slowing or pausing the drip usually helps within minutes.
Premedication can reduce these reactions. Most infusion protocols call for a pain reliever like acetaminophen, an antihistamine, or an anti-inflammatory before the IV starts. Some patients who react repeatedly also receive a steroid beforehand. The specific medications and doses vary by prescriber, but the goal is the same: blunt the immune response your body mounts against the incoming antibodies.
Hemolysis in Non-O Blood Types
One of the more underappreciated risks of IVIG is hemolysis, where red blood cells break down faster than normal. This happens because all IVIG products contain small amounts of anti-A and anti-B antibodies. If your blood type is A, B, or AB, those antibodies can attack your red blood cells.
The risk is not trivial at high doses. Research from Canadian Blood Services found that hemolysis occurs in roughly 35% to 37% of non-O patients receiving high-dose IVIG, with about 10% of those cases being severe or potentially life-threatening. At lower replacement doses (the kind used for immunodeficiency rather than autoimmune conditions), the risk drops substantially. Signs of hemolysis include dark urine, unusual fatigue, and a sudden drop in energy a day or two after infusion. Blood tests showing a falling hemoglobin level confirm it.
Kidney Problems
IVIG can occasionally cause acute kidney injury. This risk is highest in older patients, those with preexisting kidney disease, and those receiving high immunomodulatory doses for conditions like autoimmune neurological disease. Historically, sucrose-containing IVIG formulations were the primary culprit, since the kidneys struggle to process large amounts of sucrose delivered intravenously. Most modern products have moved away from sucrose for this reason.
That said, kidney problems aren’t exclusive to sucrose-based products. At least one case report documented kidney dysfunction in a young, otherwise healthy patient receiving a glycine-based (sucrose-free) IVIG product with no pre-existing risk factors. If you have any history of kidney issues, your provider will likely monitor your kidney function with blood tests before and after infusions.
Blood Clots
IVIG increases the risk of thromboembolic events, including heart attacks, strokes, pulmonary embolism, and deep vein thrombosis. In one study of 112 patients on long-term IVIG therapy published in Neurology, 12 thromboembolic events were documented: six heart attacks, two strokes, and one pulmonary embolus.
The risk is higher if you already have cardiovascular risk factors like high blood pressure, diabetes, a history of blood clots, or prolonged immobility. High-dose regimens and rapid infusion rates also increase the danger. Staying well-hydrated before and after your infusion is one of the simplest things you can do to lower this risk, since dehydration thickens the blood and makes clotting more likely.
Anaphylaxis and IgA Deficiency
True anaphylaxis during IVIG is rare, but it’s the reaction that concerns providers most. The highest-risk group is people with complete IgA deficiency, defined as IgA levels below 0.05 mg/dL. These individuals can develop antibodies against IgA itself, and when IVIG delivers a dose of IgA-containing product, the result can be a severe allergic reaction.
Detecting true IgA deficiency requires a specialized, highly sensitive lab test. Routine screening isn’t done for every patient. Instead, testing is typically reserved for anyone who has had one anaphylactic reaction or two severe allergic reactions to blood products. If you’re confirmed IgA-deficient with anti-IgA antibodies, IgA-depleted products are available.
Delayed Skin Reactions
Skin reactions to IVIG are uncommon, but a distinctive pattern exists. The most frequently reported rash is a blistering form of eczema called pompholyx. It typically begins 8 to 10 days after the infusion, starting as small, intensely itchy blisters on the palms. From there, it can spread into a more widespread eczema-like eruption across the body. In severe cases, the skin becomes red and inflamed nearly everywhere.
Because of the delay between infusion and rash, many patients don’t immediately connect the two. If you develop unexplained blistering or itching on your hands a week or so after treatment, it’s worth flagging for your care team so they can adjust your regimen or add preventive measures for future infusions.
What Affects Your Risk
Not everyone faces the same odds of side effects. Several factors shift the balance:
- Dose: High-dose IVIG (used for autoimmune and inflammatory conditions) carries more risk across the board than lower replacement doses used for immunodeficiency.
- Infusion speed: Faster rates mean more reactions. First-time infusions are run more slowly than subsequent ones for this reason.
- Time since last infusion: Longer gaps between treatments increase the chance of a reaction, since your body partially “resets” its tolerance.
- Blood type: Non-O blood types face a real risk of hemolysis at high doses.
- Kidney and cardiovascular health: Pre-existing conditions in either area amplify the corresponding risks.
- Hydration: Being well-hydrated before infusion reduces headache, kidney stress, and clotting risk.
Most people tolerate IVIG well enough to continue long-term therapy, and the common side effects tend to become milder with repeated infusions. The serious complications, while important to know about, are infrequent and largely predictable based on your individual risk profile.