Menthol and G6PD deficiency: what to know

G6PD helps red blood cells handle oxidative stress. With G6PD deficiency, some people can develop haemolysis, meaning red blood cells break down more quickly, after a trigger such as an infection, a medicine or a chemical exposure. Menthol may appear in lozenges, rubs, inhaled products, cosmetics and traditional preparations, so the full ingredient list matters. Evidence and exposure can differ between products; do not assume that a familiar smell means the product is suitable.

Tell every doctor, dentist and pharmacist that you have, or may have, G6PD deficiency. Show them the exact product, label and intended route of use before starting it. Avoid borrowing medicines or using concentrated preparations without advice. Ask whether an alternative is available, especially during an infection or when treating a child. Keep your diagnosis recorded with your medicines, and follow advice about screening and known triggers.

Seek urgent medical care if you develop dark urine, pale skin, yellowing of the eyes, unusual weakness, fast breathing, dizziness or fainting after a new product, medicine or infection. These symptoms can indicate red-cell breakdown or anaemia and should not be watched at home if they are pronounced or worsening.

Ask whether your diagnosis has been confirmed, which ingredients to avoid, whether a blood test is needed, and what action plan to follow if fever, dark urine or marked tiredness appears.