Melasma, post inflammatory hyper pigmentation and dead skin cell buildup causes splotchy skin, according to Everyday Health. Darker skin tones are more prone to becoming splotchy due to the higher amount of melanin in the skin.
Hormone fluctuations in the skin caused by pregnancy or birth control coupled with exposure from the sun results in the face appearing splotchy, according to Everyday Health. This condition is called melasma, also known as pregnancy mask. Skin that has withstood a trauma such as a rash, bruise, pimple, cut or scrape can become discolored and dark, and dead skin cell buildup on the knees and elbows can also cause splotches on the skin. Shaving or waxing irritation and everyday friction in the underarm area also causes dark splotches.
Everyday Health advises taking care of dead skin cells with a gentle exfoliator, such as a scrub or cream that contains urea and a low level of glycol acid, and consulting a dermatologist about using a prescription cream that contains hydroquinone to fade dark spots and prevents reoccurrences. Sunscreen with an SPF of 30 or higher is recommended by Everyday Healthy to protect the skin from over-producing melanin and causing splotching. Medical advice should be sought to determine if skin irritations that result in splotches occur from avoidable allergies.