Blemishes are marks or areas of discoloration on the skin. They can be raised off of the skin or flat, and come in a range of colors. Since there are many different types of blemishes with many different causes, the treatment for each is a little different. Common types include acne, scars, birthmarks, age spots, and an uneven skin tone.
Acne
One of the most common blemish-causing conditions is acne. This can cause both raised pustules and pimples as well as flat blackheads and whiteheads. These happen when a hair follicle gets clogged with a naturally-produced oily substance called sebum, dirt, or bacteria, and can also be caused by ingrown hairs. Most people have acne during puberty, when hormonal changes cause the body to produce too much sebum, which increases the changes of clogs. Over-the-counter (OTC) cleansers and medications can reduce sebum, soothe inflammation, and clean out pores for people with mild or moderate acne, but those with severe acne may need prescription anti-inflammatories and medications to regulate hormonal changes.
Scars
Scarring is another of the most common blemishes. It's caused by too much collagen building up after an injury, and can range widely in size, color, and texture. Though most scars fade over time, using skin oils containing vitamin C, chemical peels, dermabrasion, and laser therapy can reduce the appearance of large or brightly-colored scars. One exception to this is keloid scarring, which continues to grow even after skin has healed, and doesn't respond well to many types of treatment. Radiation therapy, corticosteroid injections, and cryosurgery may reduce the appearance of these types of scars.
Birthmarks
Blemishes that appear as flat patches of discoloration that are present at birth or develop when a person is very young are called birthmarks. They can range widely in size, and are typically black or brown, as in the case of moles; or red, as in the case of port wine stains and stork bites. They're almost always benign, and are caused by too much pigmentation in one particular area, or blood vessels coming close to the surface of the skin. Since they're usually just a cosmetic problem, they can usually be treated with steroids or laser treatments, or can be frozen off or surgically removed.
Age Spots
Sun exposure may cause age spots or liver spots in older people or younger people who tan a lot. Like birthmarks, they're generally flat, and can be found anywhere on the body, though they're most common on the face and hands. They usually look like small gray, black, or brown marks, and can be treated with skin-bleaching creams.
Uneven Skin Tone
A blotchy skin tone is also a very common, though often more subtle, form of blemish. Also known as hyperpigmentation, it's caused by an irregular overproduction of melanin. Since melanin production is influenced by sun exposure, hormones, and skin injury, too much of any of these things can change skin tone for the worse. Depending on the type of discoloration and the underlying cause, an uneven skin tone can be treated by exfoliation, topical creams, and medications affecting hormone production.
Preventing Blemishes
Though it's impossible to prevent birthmarks, the chances of getting other types of blemishes can be greatly reduced through proper skin care. Wearing sunscreen and avoiding tanning can help prevent age spots and can help with an uneven skin tone, and staying hydrated can help keep skin looking healthy. Washing the face on a regular basis with a cleanser that matches a person's skin type is also important, as is regularly moisturizing the face. Additionally, proper wound care, breathable bandages, and anti-scarring cream can all reduce the chances of noticeable scars.