IVIg vs SCIg for CIDP: Pros, Cons, Side Effects & What Switching Really Feels Like

I live with Lewis–Sumner syndrome, a very rare variant of an already rare neurological autoimmune disorder known as Chronic Inflammatory Demyelinating Polyneuropathy.

As I’ve said before – why just have a simple pain in the ass when you can fall ill with something almost no one has heard of?

CIDP is notoriously hard to diagnose. It often mimics other neurological conditions, comes with different variants and degrees of severity, and can overlap with other conditions—so, naturally (and almost inevitably), there’s a whole maze of treatments to navigate.

If you’re living with CIDP (Chronic Inflammatory Demyelinating Polyneuropathy) or one of its rare variants like Lewis–Sumner syndrome, chances are you’ve already heard about immunoglobulin therapy.

Two of the most common treatment options—IVIg (intravenous immunoglobulin) and SCIg (subcutaneous immunoglobulin)—deliver the same IgG antibodies, but the day-to-day experience of each can feel very different.

I’ve lived with CIDP, and now I have experience with both IVIg and SCIg.

When my neurologist suggested switching from hospital-based IVIg infusions to home-based SCIg injections, I couldn’t help but wonder:

Which treatment is more effective?

What are the side effects?

Is SCIg really easier than IVIg?

And what does switching actually feel like in real life?

In this post, I compare IVIg vs SCIg from a patient’s perspective, including the pros and cons of each treatment, how the two therapies differ in terms of convenience, side effects, and quality of life, and what I wish I had known before making the switch.

(would not make any difference at the end of the day cos I wanted to get out of hospital so bad; nevertheless, I wish I knew.)

If you’re considering changing your CIDP treatment plan—or simply want a clearer picture of your options—this guide is for you.

Switching from IVIg to SCIg was thrilling—finally, the idea of freedom from hospital visits!—but I still had plenty of doubts and fears. The headings in this post are the issues I wrestled with, and here I share the answers I found along the way.

IVIg vs SCIg for CIDP: 10 Common Questions Answered

1. How IVIg and SCIg Work?

IVIg is delivered through a vein every three to four weeks, quickly flooding the bloodstream with antibodies. This fast delivery can help when a patient needs a strong, immediate effect.

SCIg, in contrast, is administered under the skin, usually weekly or every two weeks. The absorption is slower, resulting in steadier antibody levels.

Despite these differences, research shows that both therapies are similarly effective at maintaining muscle strength and preventing relapses, with SCIg often helping reduce the “wear-off” effects some patients notice with IVIg.

2. What are IVIg vs. SCIg Key Differences?

The biggest difference is how the body experiences the treatment.

IVIg creates rapid high peaks of antibodies, which can sometimes trigger side effects like headaches, blood clots, or kidney problems.

SCIg spreads the dose out more gradually, which usually leads to fewer systemic side effects—up to 22% lower risk—and better overall tolerability.

Plus, many patients love the convenience of self-administering SCIg at home, avoiding frequent trips to the clinic.

I am this patient!

3. Are IVIg and SCIg Equally Effective for CIDP?

When dosed correctly, both IVIg and SCIg do a remarkable job of stabilizing CIDP symptoms.

Relapse rates are comparable, and some studies even suggest SCIg can slightly improve sensory function and quality of life, simply because it allows patients more freedom and independence.

Being able to do SCIg at home brought an indescribable sense of relief—like finally slipping off a leash I’d been on, tied to hospital visits that were happening far too often for my liking.

When I first started IVIg treatment at the hospital, it was hard to accept this new, demanding reality.

The hospital stress weighed on me, and I often felt low, thinking, “Is this really going to be forever?”

4. Who Should Consider Each Option?

IVIg: Often chosen for patients with more severe disease, those who need rapid symptom control, or those who cannot use SCIg. But it’s usually avoided for patients prone to systemic reactions.

SCIg: Ideal for patients who value autonomy, want to avoid IV needles, or prefer fewer infections and more flexibility. It’s FDA (USA) and EMA (EU) – approved for maintenance therapy in adults whose CIDP has been stabilized with IVIg.

(From what I understand SCIg is approved in many countries around the world as well. Approval and availability vary by region, with some countries leading the way and others still catching up)

5. Who Decides Between IVIg and SCIg for CIDP—You or Your Doctor?

For me, it absolutely was a shared process.

I was introduced to the idea of SCIg in the spring of 2025, about four years after starting IVIg—and I welcomed it with open arms.

At the time, my neurologist could only give me a somewhat vague explanation of what SCIg was all about. She was learning too.

SCIg has been available in the U.S. and other EU countries since 2018, but in Poland, it only became an option in July 2025—meaning many doctors and patients here had to catch up and learn this new therapy.

For that reason, earlier in my CIDP journey, SCIg simply wasn’t on the table, and IVIg was the only road available.

Looking back, I think my doctor could already see me switching.

My condition, level of severity, overall fitness, maybe even my age and enthusiasm—it all played a role.

Nothing about this decision happened in isolation.

And that’s the key thing to understand: choosing between IVIg and SCIg is rarely one-size-fits-all.

I’ve heard from people who felt SCIg just wasn’t right for them. Some preferred to stick with IVIg because the idea of self-injecting felt too intimidating.

Others found the pump and the whole procedure too complicated and too overwhelming to learn.

And yes—believe it or not—some genuinely enjoy going to the hospital. For them, infusion days feel like a break from daily life, a social outing, even a hobby. (I know. I don’t quite know what to say either. But who am I to judge?)

What all of this really shows is that the decision is a partnership.

Doctors bring medical expertise to the table—disease severity, medical history, venous access, cost. Patients bring something just as important: preferences, comfort levels, lifestyle needs, and emotional readiness.

Often, treatment starts with IVIg to quickly stabilize symptoms (and when I started there was a burning need to stabilize my symptoms) and later transitions to SCIg for long-term maintenance.

Research shows that once people try SCIg, many end up preferring it for the sense of control and flexibility it offers—but that doesn’t mean it’s the right choice for everyone.

I strongly agree, especially with the “flexibility” part of it, but not only.

The bottom line?

Both IVIg and SCIg are powerful tools in managing CIDP.

The best option is the one that balances medical effectiveness with quality of life—your quality of life.

With the right guidance, honest conversations, and shared decision-making, it’s possible to find a treatment that fits not just your diagnosis, but your life.

6. What are Benefits and Drawbacks of IVIg vs. SCIg for CIDP?

Both IVIg and SCIg use the same immunoglobulins, but they can feel very different once you’re actually living with them.

IVIg is usually given in high doses through a vein every three to four weeks. For many people, it brings relatively fast symptom relief, especially early on.

The downside?

Those big doses can create peaks and troughs in IgG levels.

Toward the end of the cycle, some patients notice the familiar “wear-off” feeling creeping back in—fatigue, weakness, or that unsettling sense that your body is slowly unplugging again.

For me, when that sensation started returning in my hand and arm, it was traumatic every single time.

I still don’t fully know why it hit so hard, but I think part of it lived deep in my psyche: a quiet, glowing hope that this time my arm, my muscles, my nerves—my hand—would stay strong, stand up to a rebellious, rogue, or maybe just deeply confused immune system.

That they would hold their ground. That CIDP might, just for once, forget about me.

Add to that the regular hospital or clinic visits, and IVIg can start to feel like life is planned around infusions rather than the other way around.

SCIg, by contrast, is absorbed slowly through weekly, biweekly (or monthly even) injections under the skin. The IgG levels stay much steadier, which for many people means fewer ups and downs.

Being able to do treatment at home—without veins, infusion chairs, or hospital schedules—can be a huge quality-of-life upgrade.

The trade-off?

SCIg often causes local skin reactions at first: redness, swelling, or itching at the injection sites. The good news is that these usually ease with time and experience.

In short, IVIg can feel more intense and medically “heavy,” while SCIg tends to blend more gently into everyday life.

7. Who Might Consider Switching to SCIg?

SCIg isn’t for everyone, but it can be a great option for the right person at the right stage.

Patients who are already stable on IVIg and looking for more independence are often ideal candidates.

SCIg can be especially appealing if venous access is difficult, hospital visits feel emotionally draining, or your schedule simply doesn’t leave room for frequent infusions.

It’s also a good option for people who want more control over when and where treatment happens.

It’s not meant for acute flare-ups where rapid, high-dose treatment is needed.

And for some people—such as those with significant skin issues or poor absorption under the skin—IVIg may still be the better fit.

As always with CIDP, it’s not about “better” or “worse,” but about what works best for your body and life.

8. How Do IVIg and SCIg Dosing Schedules Differ?

IVIg dosing often looks like this: a loading phase in the clinic, followed by maintenance doses such as 1 g/kg every three weeks or 2 g/kg every four to six weeks.

It’s effective, but it can feel like riding a wave—strong at first, then slowly tapering off.

SCIg spreads the same total amount of immunoglobulin out over time. Weekly doses (often around 0.2–0.4 g/kg) keep levels more even, helping avoid those dramatic highs and lows.

Everything happens at home, on your own schedule, with dose adjustments based on symptoms and response rather than a rigid calendar.

Different rhythm, same goal: keeping you stable.

9. Side Effects and Safety: What to Expect?

With IVIg, side effects are more often systemic.

Headaches, flu-like symptoms, aseptic meningitis, blood clots, or kidney strain can occur—largely because of the sudden IgG spikes. Some studies report systemic side effects in up to 30% of infusions, though severity varies widely.

SCIg tends to shift side effects from “whole body” to “local.”

Redness, swelling, or tenderness at injection sites are common early on (many people experience them at first), but they usually settle as the skin adapts.

Overall, SCIg is associated with about 22% fewer adverse events, thanks to its slower, gentler absorption.

Serious reactions like anaphylaxis are rare with both therapies, but SCIg generally reduces infusion-related stress on the body.

10. What Studies Say About Relapse Rates?

Clinical trials back up what many patients report in real life: SCIg works just as well as IVIg when dosed correctly.

The PATH* (go to an explanation under the disclaimer) study showed low relapse rates with SCIg at higher weekly doses, comparable to IVIg maintenance therapy.

Other trials and meta-analyses—including more recent reviews—confirm that SCIg is non-inferior to IVIg for preventing relapses.

Just as importantly, many patients report preferring SCIg because it fits more smoothly into daily life.

Again – I AM in this very group!

Summary Comparison Table

Note: This table is based mostly on U.S. research and guidelines, but the key differences it highlights—how treatments are given, side effects, and lifestyle impact—apply to many CIDP patients worldwide.

Aspect	IVIg	SCIg	Notes/Winner
Administration	Clinic IV every 3-4 weeks, 2-5 hours	Home SC weekly/biweekly, 30-60 min/site	SCIg (convenience, autonomy) pmc.ncbi.nlm.nih
Efficacy/Relapse Rates	Comparable stabilization; peaks/troughs	Steady levels; non-inferior, possible QoL edge	Tie (PATH trial data) neurologylive
Common Side Effects	Systemic: headache, thrombosis (20-30%)	Local: redness/swelling (50-70%, fades)	SCIg (fewer severe AEs) rarediseaseadvisor
Dosing Example (70kg)	1 g/kg every 3 weeks (~200g/year)	0.2-0.4 g/kg weekly (~600-1400g/year adjusted)	SCIg (flexible maintenance) sciencedirect
Patient Suitability	Acute/severe; poor SC access	Stable maintenance; lifestyle flexibility	SCIg for most long-term neurologylive
Annual Cost (est. US)	$30K-$50K (incl. clinic fees)	$25K-$45K (home savings)	SCIg (10-20% cheaper long-term) medicalaffairs.cslbehring
Transition Protocol	N/A	Overlap 1 week post-IVIg; supervise first doses	SCIg feasible for 88-90% pmc.ncbi.nlm.nih

[table source: Perplexity]

Final Thoughts

While I know it’s sometimes easier said than done, getting the chance to use SCIg felt like a real milestone—a breakthrough.

Yes, I paid my dues while learning the ropes: facing doubts, confronting fears about self-injections, possible side effects like allergies, weighing pros and cons, and dealing with a swollen, sometimes painful stomach.

But here I am, on SCIg now, and full of hope that it will help me stay strong and keep moving forward into the future.

Disclaimer: I’m not a neurologist, doctor, or medical expert. I’m a CIDP / Lewis–Sumner syndrome patient navigating this condition in real life and sharing my personal journey, reflections, and research along the way.

This blog exists to share information and lived experience—not to give medical advice. While most of the writing here is my own, some posts—particularly those focused on understanding CIDP and its treatments—are shaped by online research using medical publications and tools such as Perplexity. In this post, the headings reflect my personal questions about IVIg and SCIg, explored through research to better understand my own treatment options.

Everyone’s CIDP journey is different, and treatment decisions should always be made in partnership with your neurologist or healthcare provider.

* PATH STUDY – one of the key studies often mentioned when comparing IVIg and SCIg, is a large international clinical trial sponsored by CSL Behring (the manufacturer of one of the SCIg products) and conducted by neurologists and CIDP specialists across multiple countries.

The study followed people with CIDP who had already been stabilized on IVIg and then switched to SCIg to see whether it could maintain their improvement. The results were reassuring: patients receiving higher weekly doses of SCIg experienced low relapse rates, comparable to those seen with IVIg maintenance therapy.

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