If your dandruff is severe, you can a number of anti-dandruff shampoos that contain the ingredients that kill the fungi partly responsible for dandruff. Note that you should only try 1 shampoo at a time, to see which is right for you. Look for shampoos at your local drugstore or pharmacy that contain:  Zinc pyrithione: This ingredient helps to kill the malassezia fungi that is partially responsible for the development of dandruff. You can find zinc pyrithione in the brands like Head & Shoulders, Jason Dandruff Relief 2 in 1, and SHS Zinc. Salicylic acid and sulfur: This ingredient helps to soften dead skin cells on your scalp, causing them to shed and release from your scalp and can be found in Neutrogena T/Sal and Sebulex. Be aware you may experience dryness on your scalp after using a shampoo that contains salicylic acid. You can use a conditioner after the shampoo to keep your scalp moisturized. Selenium sulfide 1% to 2.5%: This ingredient helps to slow down the production of skin cells on your scalp and kill dandruff causing fungi. It can be found in Exsel, Selsun Blue, and Reme-T. However, this shampoo is not recommended for individuals with blonde or chemically treated hair, as it can discolor your hair. Ketoconazole 1% shampoo: This shampoo has a powerful antifungal effect that can treat and prevent dandruff. This ingredient can be found in Nizoral A-D shampoo. Coal tar shampoo: These shampoos can help to slow down the production of dead skin cells and prevent dandruff. This ingredient can be found in Neutrogena T/Gel, Tarsum, and Tegrin. You should not use certain types of anti-dandruff shampoo if you are pregnant or breastfeeding. Always read the instructions on the label of the shampoo before use and talk to your doctor if you have concerns about using the shampoo. Once you decide on an anti-dandruff shampoo, it’s important that you apply it properly for the most effective treatment. You can apply the shampoo once a day or every other day until your dandruff is under control. The exception is...

TL;DR in Vietnamese:
Thử dùng dầu gội trị gàu không kê đơn chứa kẽm hoặc axit salicylic. Dùng dầu gội theo hướng dẫn trên nhãn. Dùng kem dạng thuốc không kê đơn để điều trị gàu. Thoa dầu khoáng sau khi dùng dầu gội trị gàu.