Overview
About half of cases are linked to small cell lung cancer, which may be found later.
The immune system blocks signals from nerves to muscles.
Symptoms
Common signs:
- Leg weakness
Less common
- Dry mouth
- Constipation
- Droopy eyelids
When to get medical care
Causes
Immune.
Does it spread or run in families?
- It isn't contagious. You can't catch it from someone else.
Who is more likely to get it
- Smoking
Possible complications
- Falls and fall risk: From weak legs
Diagnosis
A clinician asks about your symptoms and may order tests.
The exam
A physical exam.
Tests
Tests, if needed:
- Antibody test:
- Chest CT:
Treatment
Treatment depends on the cause and how severe it is.
Self-care
- Pace activities
- Rest
Prevention
To lower your risk or prevent problems:
- Don't smoke
Which doctor treats this
- Start with your primary care provider (family doctor or internist).
- They may send you to a neurologist (brain and nerve doctor).
Living with it
Support groups and helplines
- Genetic and Rare Diseases Information Center (GARD): Free NIH information on rare diseases, including where to find experts and patient groups.
- National Organization for Rare Disorders (NORD): Patient groups, help finding care, and aid programs for rare diseases.
Children, pregnancy, and older adults
- Smokers over 50: Higher risk.
Pregnancy and breastfeeding
- If you're pregnant or planning to be, tell your prenatal provider about this condition.
- Don't start or stop any medicine on your own. Some are safe in pregnancy and some need to be changed.
- Ask before taking any pain reliever. The FDA advises avoiding ibuprofen and naproxen after 20 weeks unless your doctor says to.
- Breastfeeding: Most medicines are fine, but ask. The NIH LactMed database lists what's known about each one.
Outlook
Treatment improves strength for many.
Treating cancer helps.
Getting ready for your visit
Bring a list of your symptoms and medicines.
What to bring
- A list of your medicines and supplements
- Notes on when symptoms started and what makes them better or worse
Questions to ask
- What's causing this?
- What treatment do you recommend?
- How often should I be screened for cancer?
Research studies
Research studies test new ways to find and treat health problems. Some are looking for volunteers. Talk with your doctor before joining one.
Search ClinicalTrials.gov for studies on Lambert-Eaton syndrome
Sources
Last updated 2026-11-12.