There is no fixed answer as to how long you should not wash your hair before the scalp fungus test, and it is recommended that you do not wash your hair for 1~2 days before the scalp fungus test. Scalp fungal examination is mainly to extract local dandruff or hair, and then carry out fungal microscopy or fungal culture, and then according to the results to clarify whether there is a fungal infection. There is no clear rule on how long you can’t wash your hair before performing a scalp fungus test. In order not to affect the results, it is recommended that you don’t wash your hair for 1~2 days before the scalp fungus test. Washing the hair before the scalp fungus test will wash away the dandruff and hair to be shed, which will increase the difficulty of sampling, and will also cause a decrease in the positive rate of the fungus test. Scalp fungus examination can be completed in the dermatology department of a regular hospital, or you can consult your doctor for precautions before going for the examination.