IVIg for myasthenia gravis is typically given as a total dose of 2 g/kg split over 2 to 5 consecutive days during an acute flare. For people who need ongoing maintenance, the usual schedule is a smaller dose of 0.4 g/kg every 3 to 6 weeks. The exact frequency depends on whether you’re being treated for a crisis, preparing for surgery, or managing symptoms long-term.
Acute Flares and Myasthenic Crisis
When myasthenia gravis suddenly worsens or tips into a full crisis (severe weakness affecting breathing or swallowing), IVIg is given as a short, intensive course. The standard protocol is a total of 2 g/kg of body weight, divided into daily infusions over 2 to 5 days. The most common approach is 400 mg/kg per day for 5 consecutive days, though some centers compress the same total dose into 2 or 3 days.
Improvement doesn’t happen immediately. In clinical trials, the median time to a noticeable response was about 12 to 13.5 days after starting treatment. So while the infusions themselves take less than a week, the full benefit unfolds over the following one to two weeks. This is a one-time treatment course for the flare, not a recurring schedule, though some people experience repeated exacerbations that require additional courses.
Maintenance Infusion Schedules
Some people with myasthenia gravis don’t respond well enough to standard immunosuppressive medications and need periodic IVIg to keep symptoms controlled. In these cases, a smaller dose of 0.4 g/kg is given as a single infusion, typically every 3 to 6 weeks. The interval varies from person to person. Some do well stretching to every 6 weeks, while others relapse if they go beyond every 3 or 4 weeks.
Finding the right schedule often involves trial and adjustment. Your neurologist may start with a shorter interval and gradually space infusions further apart to find the longest gap that still keeps your symptoms stable. If symptoms creep back before the next scheduled infusion, that’s a sign the interval needs to be shortened. There’s no single “correct” frequency, and the goal is the least-frequent dosing that maintains function.
It’s worth noting that recent international guidelines (including 2024 Nordic guidelines and expert consensus) position IVIg primarily as a rescue therapy for crises and acute flares rather than a preferred long-term treatment. Newer medications targeting specific parts of the immune system are increasingly available for people whose disease is hard to control with standard drugs. Still, maintenance IVIg remains a practical option when those alternatives aren’t accessible or effective.
How Long Each Infusion Takes
A single IVIg infusion session generally takes several hours. The infusion rate is started slowly and gradually increased if you tolerate it well. During an acute 5-day course, you can expect to spend a significant part of each day at an infusion center or hospital. Maintenance infusions, which involve a smaller volume, are shorter but still require a few hours per visit including monitoring time afterward.
Common Side Effects During Treatment
About 59% of people receiving IVIg experience some kind of side effect, though most are mild and manageable. The most common reactions are vasomotor symptoms (chills, nausea, chest tightness, flushing) occurring in roughly 30% of patients, and headaches in about 26%. Fever, rash, and general fatigue also occur. Most of these improve when the infusion rate is slowed down or when over-the-counter medications are given for symptom relief.
Because side effects tend to be tied to how fast the infusion runs, the first session is usually given at a cautious pace. If you’ve tolerated previous infusions well, subsequent sessions can often be sped up slightly, reducing the total time spent in the chair.
Subcutaneous Immunoglobulin as an Alternative
Subcutaneous immunoglobulin (SCIg) delivers the same medication through a small needle under the skin instead of into a vein. It can be self-administered at home, which is a significant practical advantage for people on a maintenance schedule. SCIg is generally given more frequently (often weekly) in smaller doses, rather than in one large infusion every few weeks. It tends to cause fewer of the systemic side effects like headache and chills that come with intravenous delivery.
No randomized trials have directly compared IVIg and SCIg in myasthenia gravis, so the evidence for switching is based on smaller studies and clinical experience rather than head-to-head data. That said, people who transition from IVIg to SCIg generally maintain the same level of symptom control while reporting better quality of life and more independence. If the logistics of traveling to an infusion center every few weeks are a barrier, SCIg is worth discussing with your neurologist.