Thank you for your question!
First of all you need to prevent further
hyperpigmentation from occuring, by using sun protection every day with spf 30 or higher, and re applying it in case of sweating every two hours.
You should treat your face very gently, because the chemicals in some products, can lead to sun sensitivity thus produce more pigmentation.
I advice you use a gentle face wash, twice a day, apply every morning sun protection, and you can use at night a product that contains
kojic acid, arbutin, licorice extract,
glycolic acid or niacinamide, as these are lightening agents. Be careful to wear sunglasses and hat, and stay out of the sun during summer months when using such agents, as the skin under these agents is more sensitive to sun, in risk to burn, and to develop more pigmentation again.
I wish you good luck. I hope this helps! Feel free to contact me again if anything is unclear.
Dr. Migena Gega