When all the ink is gone what whitening agent can be used for post inflammatory hyperpigmentation?

Hello and thank you so much for your question! The strongest lightening agent is called hydroquinone. At a strength that is useful it should be prescribed by your doctor. Usually a 4% cream is sufficient and requires a prescription. However, hydroquinone is a very serious ingredient as you should have a very healthy liver, should be on birth control and take breaks every two months when you are on it. Getting pregnant while using this may be extremely harmful to the fetus. Other less serious, but helpful lightening agents might include kojic acid, azuleic acid or glycolic acid. The company Glytone has an excellent Skin Lightening Cream (4% hydroquinone - requires a doctor to ok you buying it) and one called Enhanced Brightening Cream (with non-hydroquinone agents). I always see lightening of PIH work better in the winter time (just like when we lose our tan over the winter). Good luck!