Crab allergy test (specific IgE)
Quick answer: This blood test measures IgE antibodies against crab, a common shellfish allergen. Doctors usually order it when you have had symptoms such as hives, swelling or breathing trouble after eating crab or other shellfish.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
How the test is done
- 1A nurse confirms your details and the allergen requested
- 2A vein near your elbow is cleaned
- 3A needle collects a tube of blood
- 4The lab measures IgE that binds to crab proteins
What your results can mean
Reading your report
A positive result shows sensitisation, not always a true allergy, so your doctor matches it with your symptoms.
If the result is outside the usual range
A raised level shows sensitisation to crab, which can match a shellfish allergy. Positive results can also come from cross-reaction with prawns, dust mites or cockroaches, so history matters.
Who usually has this test
People who have had hives, swelling, vomiting or breathing trouble after eating crab or other shellfish.
Risks and aftercare
No special aftercare; avoid crab until your doctor has discussed the result if you have reacted before.
Names and options
Also called: crab IgE, shellfish allergy test, crab allergen
Listed by the hospital as
- ALLERGEN, CRAB
Questions about this test
If I am allergic to prawns, am I allergic to crab?
Often yes. Crab, prawns and lobster share a protein called tropomyosin, so allergy to one often goes with the others. Your doctor will advise what to avoid.
Can cooking crab remove the allergy risk?
No. The main shellfish allergen is stable to heat, so cooked crab can still cause reactions.
Can a negative crab IgE mean it is safe to eat?
A negative result makes allergy less likely, but it does not prove that crab is safe for you. If you have had a serious reaction, discuss any food challenge with an allergy specialist first.
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34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.