Body and biology
What Is HLA-B*1502? The Carbamazepine Gene Test Explained
HLA-B*1502 · say it: aych-el-ay BEE fif-teen oh-TOOAlso written: HLA-B*15:02, HLA-B 1502, HLA-B1502 allele
Short answer
HLA-B*1502 is a gene variant that greatly raises the risk of serious skin reactions to carbamazepine and some related medicines.
What it means
HLA-B*1502 is one version (allele) of an immune system gene called HLA-B. It is much more common in people with ancestry from parts of Asia, including many people of Han Chinese, Thai, Malaysian, Filipino and Indian ancestry, and is uncommon in many other groups. Carrying it does not cause illness by itself.
It appears as a boxed warning on carbamazepine labels, and is mentioned on some related medicines such as oxcarbazepine and phenytoin, because people who carry it have a much higher risk of Stevens-Johnson syndrome and toxic epidermal necrolysis when taking them. Labels advise testing for HLA-B*1502 before starting carbamazepine in people with ancestry from at-risk populations; if positive, the medicine is usually avoided unless the benefit clearly outweighs the risk.
A negative test lowers this particular risk but does not rule out every skin reaction, so a new rash still needs urgent attention. Other HLA variants are linked to reactions with other medicines.
Where you may see it
- Boxed warnings on carbamazepine labels
- Pharmacogenetic test reports
- Neurology and pain clinic letters
📄 How it looks on a report
HLA-B*1502 genotype: Not detected.
🙅 What it does not mean
- A positive result does not mean you are ill; it affects which medicines are safest for you.
- A negative result does not rule out all skin reactions to carbamazepine.
- The test is not needed by everyone; it is aimed at people with ancestry from higher-risk populations.
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “HLA-B*1502”
Plain-English explanations of each medicine, from its official FDA label.
- Carbamazepine
a mood stabilizer, and an anticonvulsant (seizure) medicine, according to the label
- Lamotrigine
An anti-epileptic (seizure) medicine and mood stabilizer. The label describes it as an anti-epileptic drug of the phenyltriazine class that is chemically unrelated to other anti-epileptic drugs.
🔗 Read more from trusted sources
- “HLA-B*1502” on MedlinePlus ↗
US National Library of Medicine
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.