Sometimes a dirty neck isn't really a dirty neck. You may have sun-damaged skin, or wrinkles in which oil and dead skin cells collect. You may be over-washing your neck, stripping it of natural oils and contributing to dry, dead surface skin. When you exfoliate dead skin cells on your face, you may forget to exfoliate your neck as well. You may also neglect to moisturize your neck and apply sunscreen as you do on your face.
Exfoliate the skin on your neck when you take a shower to remove dead dry skin cells and grime. Use a commercial exfoliant cream or a handful of salt or sugar with a drop or two of liquid soap to scrub the back of your neck, as well as other areas of skin such as your arms and legs that are exposed to sunlight, grime, oil and sweat.
Bleach your skin gently with hydrogen peroxide or lemon juice applied with a cotton ball. You won't see immediate results, but over a period of time your skin tone will even out and look cleaner.
Moisturize your skin after every shower. Exfoliating not only removes dry dead skin cells, it can also remove some of the natural protective oil from your skin. Replace that oil with a moisturizing cream or lotion applied while your skin is still damp. This retains moisture and also provides a barrier to grime.
Apply sunscreen to your skin every day, including your neck and any other areas that may be exposed to the sun, such as your face, ears, scalp, chest, arms and legs.
Carry a damp handkerchief in a plastic baggy. Sprinkle it with rosewater, orange blossom water, or a drop or two of essential oil. Use it to wipe away sweat, grime and dry dead skin cells during the day. Reapply sunscreen as needed throughout the day to continue to protect your skin.
Exfoliating too forcefully or too long can irritate your skin and lead to inflammation. Exfoliate lightly and do it regularly for the best results.
Have your skin, especially exposed areas like your neck, examined once a year for signs of skin cancer.
If the skin on the back of your neck stays dirty-looking although you use meticulous skincare practices, see a dermatologist to rule out any dermatological conditions such as acanthosis nigricans, which causes dark streaks in skin folds on the neck and other areas of the body.