Hey, Pimples at this age could be due to harmonal variation its quite common ,wash face twice daily avoid dust and pollution, don't puncture pimples it turns black, let it fade on its own , don't apply steroids without prescription . Lemon contains astringents and Vitamin C; it also removes the toxins from the body when consumed with warm water. So, use lemon to remove the dark spots on the skin. Squeeze out the extract of lemon and apply it on the dark spots with the help of cotton balls. The best results will be yielded when the application is repeated on every second day.