Why Do I Have Dark Spots on My Skin?

August 24, 2019

Why Do I Have Dark Spots on My Skin?

If you’re over the age of 50, you’ve probably noticed dark spots on your skin, likely on your hands, face, arms, and shoulders. If you’re fair-skinned or spend a lot of time in the sun without using sunscreen, you may notice these dark patches showing up even in your 20s or 30s. Most of the time, these brownish spots, also called photoaging, solar lentigines, age or liver spots, are harmless — but are unsightly and make us appear older. And once age spots form, they tend to remain and may even become darker or more widespread unless we take steps to protect our skin. The medical name for the patches is hyperpigmentation. Let’s examine what causes dark spots on our skin and how we can prevent them.

What Role Does the Sun Play in Developing Dark Spots?

If you’ve ever basked in the sun at the beach, lake or pool, you know how great it can feel. Even taking a walk on a bright, sunny day can lift our mood. After all, our bodies need sunshine to produce vitamin D. How? Our skin cells contain a precursor to vitamin D. When we expose our skin cells to the sun’s ultraviolet rays (a form of radiation), it triggers a metabolic reaction which converts the precursor to a form of vitamin D our bodies can use. Our bodies can’t really end up with too much vitamin D from sun exposure alone.

However, it’s very easy to expose our skin to too much ultraviolet radiation, which causes irreversible damage. Tanning beds use ultraviolet radiation, which can be particularly harmful to our skin because they expose our skin to extremely high doses in a short time frame. Dark spots are one sign our skin has received too much exposure to ultraviolet radiation.

How Do Age Spots Form on the Skin?

Age spots are not to be confused with moles or melanoma, a dangerous form of skin cancer that can spread throughout the body and can even be fatal. Normal moles usually form during childhood and are not connected to ultraviolet radiation.

Our skin contains cells called melanocytes, which produce and store melanin. Melanin is a pigment that gives our skin, hair, and eyes their color. If your skin, eyes or hair are brown, you have higher levels of melanin than blondes and fair-skinned people. Melanin protects our skin from ultraviolet radiation by absorbing it. When our skin cells receive too much ultraviolet radiation, they produce more melanin to protect themselves. Dark spots develop when excess melanin forms deposits and becomes clumped together. Since the melanin deposits are darker than the surrounding skin, they stand out. People of any race can develop hyperpigmentation.

Is Sun Exposure the Only Cause of Dark Spots?

Exposure to ultraviolet radiation is by far the most common reason we develop hyperpigmentation, but other causes exist.

Hormonal Changes: Women who take birth control pills or are pregnant can develop dark spots called melasma, aka the “mask of pregnancy.” Melasma spots tend to be larger and more widespread than age spots and can also develop on the abdomen. If you have darker skin, you are more susceptible to developing melasma.
Wounds: Burns, cuts and insect bites can cause post-inflammatory hyperpigmentation.
Skin Ailments: Eczema, acne, and psoriasis can leave scars, which results in post-inflammatory hyperpigmentation.
Medication: Some medications such as tetracycline, psychotropic drugs, phenytoin, antimalarial, cytotoxic and non-steroidal anti-inflammatory drugs can cause hyperpigmentation.
Diabetes: A variety of skin conditions such as acanthosis nigricans, a dark patch or band of darkened skin, can indicate pre-diabetes or diabetes.

Can Age Spots Be Prevented?

Yes, to a certain extent! The number one defense against developing age spots is protecting our skin from ultraviolet radiation. As noted above, we need to expose our bare skin to the sun for vitamin D synthesis, but the amount of time is minimal. A general rule of thumb is half the time it takes your skin to burn. If you’re fair-skinned, 10 or 15 minutes in the sun may be sufficient. If you live in the far northern or southern hemisphere or have darker skin, you may need more time. Most of us receive enough sun exposure going about our day, especially during the non-winter months.

Sunscreen is a must and not just any sunscreen. You’ll want a sunscreen with an SPF (sun protection factor) of at least 30 — and that protects from both UVA and UVB rays. These sunscreens are usually labeled “broad spectrum.” Many sunscreens on the market use chemicals such as octinoxate, avobenzone, and oxybenzone as the active ingredients. When applied, our skin absorbs the chemicals. When the sun’s ultraviolet rays reach the chemicals, they convert the radiation to heat and then release it.

You might be seeing a lot of new sunscreens on the market called “mineral” or physical sunscreens. These contain minerals such as zinc oxide and titanium dioxide, which sit on top of our skin and create a physical block. The earlier versions of mineral sunscreens did not absorb well into the skin and left a white, chalky appearance. Newer versions absorb better or contain a tint that blends into our natural skin color.

Both types of sunscreen work well at preventing sun damage, so it’s a matter of preference. Some sunscreens contain both chemical and physical blocks. The key is to apply enough sunscreen and reapply every two hours or more often if you’ve been in the water or sweating.

Studies have found that some of the chemicals used in sunscreens are harmful to our health and the environment, including coral reefs. Some coastal areas such as Hawaii have blocked the sale of sunscreens containing oxybenzone and octinoxate to protect coral reefs. Mineral sunscreens are usually deemed safer for the environment and are often labeled “reef-friendly” or “reef safe.” If you have sensitive skin, chemical sunscreens can be irritating — opt for a mineral one instead.

The Vitamin D Council and many dermatologists say sunscreens don’t protect us from all types of skin cancer, so it’s better to cover up instead. Fortunately, now many clothing manufacturers are making attractive “rash shirts” and other cover-ups that allow us to swim or engage in outdoor activities. A wide-brimmed hat is an excellent way to prevent damaging radiation from reaching our face, scalp, and neck.

If heading to the beach or pool covered from head to toe isn’t going to happen for you, bring a beach umbrella or sit in the shade. Just remember, you’ll still need sunscreen since water reflects sunlight and radiation can reach your skin. And don’t forget to use sunscreen even in winter, especially if you spend time in snow-covered areas since snow also reflects sunlight.