Determine What’s Going On

To figure out the best and safest treatment for your specific situation, it’s important to take some time to determine what’s causing your darkening skin. Treatment varies depending on the cause, so this step is really important.

Protect Your Skin

“If friction is the primary concern, then a good skin-lightening approach would be to protect the knees from trauma with physical barriers like clothing or knee pads,” Baron says. Avoiding friction and pressure on the knees is helpful because it reduces the buildup of skin cells and darkening of the skin, Shirazi explains.

Use Alpha- or Beta-Hydroxy Acids

“When your skin is repeatedly damaged, even just from pressure or slight rubbing over a period of weeks or months, the epidermis will ramp up its barrier functions by overproducing and retaining its surface cells,” Baron says. “In this hyper-activated state, the melanin-producing cells are also sent into overdrive.”

For this type of darkened skin that’s been damaged and thickened over an extended period of time, alpha- or beta-hydroxy acids such as glycolic acid can help dissolve dead cells, Baron says. A strong retinol can then help return the skin’s cell turnover to a healthy, normal rate. 

Shirazi recommends using a medicated spray like AziMD’s the ONE ($38) with glycolic and salicylic acid, which lightens hyperpigmentation and removes skin buildup.

Moisturize

Keeping your skin well moisturized with rich skin emollients like lanolin and plant oils is a good way to treat dark skin on the knees that arises because of friction, Baron says. Additionally, moisturizing with an SPF cream helps protect the skin from producing more melanin, Shirazi says.

Use Prescription-Strength Hydrocortisone

“A short course of prescription-strength cortisone ointment may occasionally be needed to break the cycle of damage and inflammation,” says Baron. “It should be noted that cortisone preparations can thin the skin, cause poor wound healing, and over-lighten the skin if they are not used with care.”

Try a Tyrosinase Inhibitor

Tyrosinase is an enzyme that plays a big role in the production of melanin, which gives skin its color. Some skincare products contain tyrosinase inhibitors, which treat and prevent hyperpigmentation and even your skin tone.

Shirazi says skincare products that contain tyrosinase inhibitors such as hydroquinone, azelaic acid, kojic acid, Arbutin, and vitamin C help lighten discoloration and pigmentation.

Avoid Scrubbing

As counterintuitive as it may sound, scrubbing your knees isn’t a good idea. “The worst thing you can do to try to reverse skin darkening is to scrub it with a sand or metal file, pumice stone, or use an exfoliating product that contains any gritty material,” Baron says. “This would only add to the injury and force your skin to get thicker and darker.”

Practice Caution With Whitening Creams

In some cases, using hydroquinone creams may not be a good idea, either. Hydroquinone is a chemical compound that reduces the activity of an enzyme that’s involved in the production of melanin pigment. Products containing hydroquinone are often used to lighten dark patches of skin, but there is a bit of debate over whether the compound carries harmful side effects. Cosmetics containing hydroquinone have been banned in the European Union for more than 20 years because of mercury contamination. However, in the United States, prescription skin-lightening products that contain hydroquinone are approved by the FDA.

“Hydroquinone applied to the skin for more than two months continuously may lead to deposits of a dark material in the skin,” Baron says, adding that the risk can be eliminated by taking a two-week break for every two months of daily treatment. She suggests talking to a dermatologist who can direct you to a pharmacy or manufacturer with responsible standards in order to avoid products that may be contaminated with mercury.

Skip the Hydrogen Peroxide

“Avoid hydrogen peroxide,” Shirazi says. “As a bleaching agent as it causes damage to skin cells and may end up causing inflammation, worsening hyperpigmentation.”