An Overview of Dark Spots

Dark spots on the skin—also known as hyperpigmentation, age spots, solar lentigines, or liver spots, depending on their cause—can happen at any time, but most often appear in middle age. Most often, they are a consequence of past sun exposure or artificial UV light used in tanning beds. The spots are also associated with certain skin conditions and can occur as a side effect of some medications as well. Dark spots are generally harmless, but there are times when they could be cancerous. They can be lightened or removed if you so desire.

These spots can range from light to dark brown or black in color, are flat, and generally oval-shape.

Dark spots can develop anywhere, but they are most likely to appear on the parts of the body that receive the most sun exposure, including:

• The face
• The backs of the hands
• The shoulders
• The arms
• The back

While usually small, several spots can group together and form larger areas of darkened skin.

Dark spots are the result of the overproduction or collection of melanin (skin pigment) and/or free radical damage.

Exposure to UV light: Whether from the sun or from an artificial source, such as tanning beds—is the most significant cause. Hyperpigmentation often starts to take hold during middle age when the skin starts to show the consequences of sun exposure, especially if sunscreen and other sun-protective measures were not used. Those with light hair or skin, and who have had severe and/or many sunburns are at particular risk.

The following other causes, however, may be at play—either alone or in conjunction with one another or UV exposure.

Skin Conditions: There are several different skin conditions and diseases that can cause dark spots and areas, though these are not the same as age-related dark spots. They include:

• Post-inflammatory hyperpigmentation: Skin discoloration following an inflammatory lesion, like acne
• Melasma: Also known as pregnancy mask
• Linea nigra: A dark, vertical line that appears lengthwise down the middle of the abdomen during pregnancy
• Chloasma: Darkened skin due to hormonal changes
• Riehl's melanosis: A form of contact dermatitis that's believed to be caused by sun exposure
• Poikiloderma of civatte: A benign condition that turns parts of the neck a reddish-brown color
• Erythromelanosis follicularis: A condition that's characterized by reddish-brown pigmentation of the face and neck

Medications: Certain medications can cause dark spots because they make the skin hypersensitive to sun exposure (photosensitive). They include:

• Estrogens, such as Vagifem, Climara, and Estrace
• Tetracyclines, broad-spectrum antibiotics such as Adoxa (doxycycline), Declomycin (demeclocycline), and Minocin (minocycline)
• Amiodarone used to treat irregular heartbeat; brand names include Cordarone and Pacerone 
• Phenytoin, an anticonvulsant; brand names include Dilantin and Phenytek
• Phenothiazines used to treat mental and emotional disorders; brand names include Compro and Thorazine
• Sulfonamides used to treat infections; brand names include Bactrim and Septra (sulfamethoxazole/trimethoprim)

Other Causes

• Pregnancy
• Liver disease
• Addison's disease
• Hemochromatosis (excessive iron)
• Pituitary tumors

Your primary care doctor or a dermatologist can usually diagnose dark spots upon physical examination. Unless a spot looks suspicious, a biopsy or further testing is not necessary. 

Dark spots don't hurt and they have the same texture as the rest of your skin. Most of the time they don't pose any health risks, so you don't have to get rid of them, although many people choose for cosmetic purposes. Dark spots can be diminished or removed completely with prescription drugs, medical procedures, and at-home treatments.

Topical treatments: Prescription bleaching creams gradually diminish the appearance of dark spots, usually over a period of several months.

Hydroquinone is the active ingredient in prescription bleaching creams. It works by inhibiting the production of melanin and should only be used on a short-term basis, as its safety has been questioned. Some research has indicated that it may be a carcinogen at higher concentrations. For this reason, the FDA has limited the concentration of hydroquinone to 3 percent to 4 percent in prescription products, and 2 percent in over-the-counter products.

There are also a number of other over-the-counter products that treat dark spots. They might diminish the appearance of spots, but may not completely eliminate them. Look for creams that contain retinoids alpha hydroxy acid, glycolic acid, deoxyarbutin, and kojic acid.

Cosmetic procedures: Medical procedures are used to treat dark spots on any part of the body and are often used in conjunction with topical treatments, though some may not be appropriate for people with sensitive skin. Options include:

• Laser treatment: This uses concentrated light energy to remove skin layer-by-layer, which burns dark spots off. Risks include bruising, swelling, redness, tightness, scarring, infection, and changes in skin texture.
• Chemical peels: These contain salicylic acid and glycolic acid, which remove the top layer of the skin, revealing healthier and more evenly toned skin beneath. Skin irritation is a possible risk.
• Microdermabrasion: There are two types of microdermabrasion, both of which physically erode surface skin cells. With crystal microdermabrasion, a machine emits fine crystals through a wand that rub against the skin and scrape away cells. For diamond-tipped microdermabrasion, the abrasive end of the wand is used for this purpose instead. The skin may be pink for a while afterward, but these techniques are considered low-risk.
• Cryosurgery: Cryosurgery fades age spots by freezing them with a liquid nitrogen solution, causing the darkened skin to peel away from the body. Risks include permanent whitening of treated areas.

As you age, dark spots may be inevitable. However, the bests way to help avoid getting dark spots (or to prevent faded ones from returning) include:

• Use SPF: Be diligent about wearing and reapplying sunscreen every two hours or sooner if you've been swimming or sweating a lot.
• Cover up: When outdoors, wear a hat (broad-brimmed is best), long sleeves, and pants. SPF fabrics can offer added protection.
• Avoid peak sun hours: UV exposure is usually greatest between the hours of 10 a.m.to 2 p.m.

Visit your dermatologist annually for a skin checkup, even if you think any oddities on your skin are harmless. Though a dark spot is likely nothing to worry about, remember that skin color changes can sometimes be a sign of cancer, particularly when paired with other changes such as bleeding, itching, and redness. (In rare cases and over a period of many years, solar lentigines develop into a melanoma called lentigo-maligna melanoma.) If your doctor sees a potentially harmful dark spot, he or she can perform a biopsy to check the skin for cancer and other concerns.