CIDP is a rare long-term condition in which the immune system attacks the protective covering around the nerves outside the brain and spinal cord, causing weakness, numbness and loss of reflexes that build up over at least two months [1,2].
This page provides general information. It does not replace advice from a doctor or another qualified healthcare professional.
Nerves outside the brain and spinal cord are called the peripheral nerves, and they carry messages between the brain and the rest of the body [3,12]. Each nerve fiber works like an electrical wire. The wire is called an axon, and wrapped around it is a layer called myelin, which acts like the plastic insulation on a cable and helps signals travel quickly. Damage to myelin is called demyelination [3].
In CIDP the immune system, which normally fights infection, attacks that myelin by mistake. That is what autoimmune means. Signals then travel slowly or get blocked, causing weakness, numbness and loss of reflexes [1,3].
The long name describes this: many nerves and nerve roots, inflamed, with damaged myelin, over a long period. An older name is chronic relapsing polyneuropathy [3,5].
How CIDP differs from Guillain-Barre syndrome. These two are regularly confused, and the difference is mostly speed. Guillain-Barre syndrome comes on quickly, usually worsening over two to four weeks, and needs urgent hospital treatment [11]. CIDP is considered its long-term counterpart. It builds over at least eight weeks and usually keeps going, steadily or in relapses, so treatment is often needed for years [2,3].
CIDP is rare, and the published numbers vary more than most sources admit.
A systematic review of nine prevalence studies found a prevalence of about 2.8 per 100,000 and about 0.33 new cases per 100,000 each year, with wide variation partly explained by the different diagnostic criteria used [4]. A patient organization gives a broader range, as high as nine per 100,000 [1].
Country figures collected by Orphanet show the spread: about 1.9 per 100,000 in Australia, 1.6 in Japan, 2.6 in the United Kingdom, 7.7 in Norway and about 12 in Egypt, against a European estimate of 3.7 [5].
All of these count people who have been diagnosed, and CIDP is both missed and wrongly diagnosed [6,7]. Figures for most of Africa, South America, the Middle East and much of Asia are not available.
The trigger is not known. There is no single cause, and infections, genetic factors and other immune factors may all play a part [1]. Evidence is growing that antibodies of the IgG type, and a part of the immune system called the complement system, help drive the damage [13,16].
A gene is an instruction inside cells, and an inherited condition is one passed from parent to child. CIDP is not inherited in that way, and no gene test can diagnose it. Inherited nerve conditions such as Charcot-Marie-Tooth disease are separate, and are often mistaken for CIDP [7,12].
CIDP can begin at any age, including childhood, and is most common in young adults and in men [1,3]. Nothing a person did caused it.
Symptoms usually begin slowly in the feet and legs and spread from there, and the early ones can be vague and hard to describe [3]. The usual pattern is fairly even on both sides of the body, affecting muscles close to the trunk and further away, with reduced feeling in at least two limbs, developing over at least two months [8]. Common symptoms are [1,3]:
Some people stay mild for years, while others get gradually worse, and without treatment about a third will need a wheelchair [3,16].
Not everyone follows that pattern. The 2021 European guideline describes several variants: a distal form affecting mainly the hands and feet, a multifocal form that is patchy and often worse on one side, and focal, purely motor and purely sensory forms, which can change over time [2,8].
When to seek urgent help. Contact a doctor or an urgent care service without delay if weakness worsens over days rather than weeks, if breathing becomes difficult, or if swallowing, speaking or facial movement is affected [11]. A few people have a rapid onset needing hospital care, though for most this never happens [3].
Diagnosis is made by a neurologist, a doctor who specializes in nerve conditions [3]. No blood test confirms CIDP, and no disease-specific marker has been found, so diagnosis rests on the pattern of symptoms and the physical examination together with several tests [9,10]:
Getting it wrong is common in both directions. In one referral study, 47 percent of people arriving at a specialist center with a CIDP diagnosis did not meet the minimum requirements, often because too much weight had been put on how people said they felt after treatment [6]. The opposite also happens: in a United Kingdom clinic, 68 percent of people who did have CIDP had first been given another diagnosis, usually Guillain-Barre syndrome, with an average delay of 21 months [7].
There is no cure, and most people improve with treatment [1].
The 2021 European guideline recommends immunoglobulin into a vein, or corticosteroids, as the first treatment for typical CIDP and for the variants, with plasma exchange if neither works. The same three are used long term, immunoglobulin also under the skin, and an immunosuppressant or nerve pain medicine added where needed [2]. In practice [1,3]:
Between half and four fifths of people respond to each of these, failing on one does not mean the others will fail, and about 15 percent respond to none of them [3].
A newer option blocks a receptor called FcRn, which controls how long antibodies survive in the blood. Efgartigimod alfa with hyaluronidase was approved in the United States on 21 June 2024, the first FcRn blocker approved for CIDP, as a weekly injection under the skin. In its main study 69 percent of 322 people improved clearly, and among those who continued, relapse risk was 61 percent lower than with placebo [13]. It is also authorized in the European Union after earlier corticosteroids or immunoglobulins [14]. Availability differs between countries [3].
Most people stay under the care of a neurologist for years, and guidance suggests reviewing whether treatment is still needed about once a year, since some reach a stable point without it [3].
Regular infusions have to be fitted around work, school, travel and caring responsibilities, which is one reason home treatment under the skin suits many people [3]. Even with good treatment, some weakness, numbness and tiredness can remain, because nerve healing is slow [1]. Physiotherapy, help with pain, practical adaptations at home and support for mental health all have a place, and free peer support is available through the organizations listed below [3,17].
Clinical trials test whether a treatment works and whether it is safe. CIDP is an active research area, so studies do come up. Deciding whether to look into one is personal, and it helps to take it in steps.
It is worth being clear on what a study involves:
Every trial has rules about who can take part, called eligibility criteria. For a CIDP study they might include a diagnosis that meets the 2021 European criteria and is checked by an independent panel, evidence that the condition is currently getting worse on a measure of disability, walking or grip strength, a set period without immunoglobulin or steroids beforehand, and no other explanation for the nerve problems such as diabetes.
trialport’s medifit helps people consider information related to possible medical suitability. It does not diagnose a condition, confirm eligibility or replace formal screening by the study team.
Explore CIDP clinical trials through trialport
Medical suitability is only part of the picture. A study can look right on paper and still be hard in practice:
trialport’s readifit helps people reflect on their understanding, motivation, time, routines, support, emotions and practical arrangements.
Useful questions to put to a research team:
Taking part is voluntary. A person can ask questions, speak with people they trust and choose not to participate.
Search for clinical trials at app.trialport.com.
Research is focused on treatments that act on the immune system more precisely, and on making the diagnosis more reliable:
Study status checked: 3 August 2026. Research moves quickly, so this list will date. For current information, search at app.trialport.com.
The GBS|CIDP Foundation International is the main condition-specific organization. Based in the United States and working internationally, it offers plain-language guides, a health navigator service, peer support and information on help with treatment costs [1].
In the United Kingdom, Inflammatory Neuropathies UK is the only charity dedicated to inflammatory neuropathies, with information reviewed by its medical advisory board, trained peer support volunteers, an emotional support service and personal grants [17].
The NHS website has no page on CIDP, though its Guillain-Barre syndrome page covers the related sudden-onset condition [11]. Orphanet holds the rare-disease reference entry [5].
Coverage elsewhere is uneven, and many countries have a general neurology organization rather than one focused on inflammatory neuropathies. Where no local group exists, the neurology service is the best starting point.
Is CIDP the same as Guillain-Barre syndrome?
No, though they are closely related. Guillain-Barre syndrome usually worsens over two to four weeks and then improves, while CIDP, its long-term counterpart, develops over at least eight weeks and usually needs continuing treatment [3,11].
Is there a cure?
There is no known cure, and most people improve a lot with treatment. Staying well for more than five years without treatment has been reported in about a quarter of people given a short course of steroids [1,3].
Is CIDP inherited?
Not in a simple way. There is no single known cause, no gene test diagnoses it, and inherited nerve conditions are separate conditions [1,7].
Why do diagnoses take so long, and can they be wrong?
Both happen. In one clinic most people with CIDP had first been given another diagnosis, with an average delay of 21 months [7]. In another, nearly half of those referred with a CIDP label did not meet the criteria [6]. A second opinion is reasonable if things do not add up.
Will I need infusions forever?
Not necessarily. Some people need only one course, others regular treatment for years, with the need reviewed about once a year [2,3].
Written by: trialport editorial team
Reviewed by: Keith Berelowitz, Founder and CEO, trialport
Reviewed on: 3 August 2026
Next review due: 3 August 2027
References last checked: 3 August 2026