Hi Thanks for your query.
You have what is known as PIH or post inflammatory hyperpigmentation.
1. Sunscreen and sunprotection- this forms the absolute cornerstone of management. You need to be on this for the duration of any treatment .
2. Apply a kojic acid cream for at least 8 weeks.
3. Chemical peels such as glycolic acid can help. You will need 4-12 treatments over the next few months.
4.
Vitamin A such as tretinoin can help.
The best treatment is a combination of the above.
Next Steps
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"Teen Acne: What Helps, What Hurts!" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/teen-acne-what-helps-what-hurts-14525/post