How do I fade acne scars?

After an acne breakout, you may notice red and brown marks.  These aren’t actually acne scars, but acne marks – what’s called post-inflammatory hyperpigmentation. True acne scars are deeper, indented, and may have a rough texture. They occur when the skin’s inner support structure has been damaged.
What causes acne marks and scars?
When the skin surface opens (like when you pop a pimple) and then heals, the affected area may have different pigmentation, texture or tone from the rest of your face. Broken blood vessels can also lead to a red or purple mark. These are surface discolorations and fairly easy to treat with anti-pigmentation creams.
Acne scars develop when the actual skin tissue is destroyed, and the body responds by making too little tissue (leading to an atrophic scar, which is indented) or too much tissue (leading to a hypertrophic scar, or keloid).
What can worsen acne marks and scars?
Picking or squeezing pimples will worsen inflammation and cause more damage. Sun exposure darkens marks and scars, and since it damages skin cells, it can also slow down your skin’s natural healing processes.
Sometimes even what we think fades scars only make them worse, like rubbing pure lemon juice on it (a popular DIY treatment that can irritate the skin) or using a very harsh, abrasive face scrub that tears the skin.
What kind of product should I look for?
There are some ingredients that are effective for acne scars. Hydroquinine, which helps control melanin, can help fade brown scars that have darkened because of sun damage. Arbutin, kojic acid and licorice are also powerful skin lighteners.
AHAS (alpha hydroxyl acids like glycolic or lactic acid) also fade discolorations and exfoliate. BHAs (beta hydroxy acids like salicylic acid) do that and dissolve any oil plugs in your pores that can lead to future breakouts. Vitamin C is known for its brightening abilities and boosts collagen production to promote healing. Retinol increases cell generation; skin cells divide more rapidly so you “shed” the cells with the discolored pigment. Note that some of these ingredients can make your skin more sensitive to the sun, so it’s really important to wear sunscreen.
For indented acne scars, you may need clinic treatments such as peels, dermal fillers, fractional laser, or radiofrequency treatments.
The best approach to acne marks: prevention
Most acne marks will fade on their own over time, but these ingredients can help fade them faster. The best approach is prevention: don’t pick at your pimples, and if you have a history of acne, take a proactive approach with an anti-acne skincare regimen.