Does Pillcheck report HLA genes?

No. Pillcheck does not currently report HLA genes.

Summary

Some genes, called HLA genes, are linked to rare but serious allergic reactions to certain medicines. Pillcheck doesn’t report these genes because the results can be misleading. Having a risk variant doesn’t mean you’ll have a reaction. Not having one doesn’t mean you’re safe, because many people who react don’t carry any known variants. If your doctor recommends HLA testing before you start a specific medicine, they can order it separately. Whatever your test results, contact a healthcare provider right away if you get a rash, fever, blisters or mouth sores after starting a new medicine.

More details

HLA genes are linked to rare but serious allergic reactions to some medications. These include Stevens-Johnson syndrome (SJS), a severe skin reaction, and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), which can also affect internal organs. Clinical guidelines (CPIC) recommend avoiding certain drugs in people who carry specific HLA variants. Examples are abacavir (HLA-B*57:01), carbamazepine, oxcarbazepine and phenytoin (HLA-B*15:02), carbamazepine (HLA-A*31:01) and allopurinol (HLA-B*58:01).

We don’t include HLA results in Pillcheck reports because these results can easily be misread:

• Carrying a risk variant doesn’t mean you will react. Most people who carry one take the medication without problems.
• Not carrying a known variant doesn’t mean you’re safe. People without any known risk variant can still have a severe reaction. A 2025 US study found that more than one-third of people with severe allopurinol reactions did not carry HLA-B*58:01, the variant usually tested for. Among Black patients in the study, the figure was 45%. Many risk variants haven’t been discovered yet, especially in populations that have been studied less.
• Most tests check only a few variants. HLA genes are among the most variable genes in the body, with thousands of known versions. A test for one variant can miss closely related ones that also carry risk.

A negative HLA result could therefore give false reassurance. Whatever your genetic results, watch for early warning signs after starting a new medication, such as a rash, fever, blistering or sores in the mouth. Contact a healthcare provider right away if they appear.

If your doctor recommends HLA testing before you start a specific medication, they can order it through a clinical lab. If you’ve had a reaction before, an allergist or dermatologist can advise whether tests such as patch testing could help identify the cause.

Learn more about medication hypersensitivity and genetics