Dark circles under the eyes are caused by a combination of thin skin, visible blood vessels, pigmentation changes, and structural shifts in the face that deepen with age. About 30% of people in some populations have noticeable dark circles, and the causes range from genetics and allergies to sleep loss and sun exposure. Most of the time, multiple factors overlap.
Why Under-Eye Skin Shows Everything
The skin around your eyes is the thinnest on your entire face. Research from Johns Hopkins measured facial skin thickness across different zones and found that the upper eyelid has a dermis (the deeper skin layer) of only about 760 micrometers, roughly a third the thickness of the skin along the side of your nose. The lower eyelid is similarly thin. This matters because thinner skin is more translucent, letting the dark blood vessels and muscle underneath show through more easily.
That transparency is the reason dark circles can look blue, purple, or reddish depending on your skin tone. You’re essentially seeing the color of pooled blood and muscle through a very thin curtain of skin. Anything that makes the skin thinner, the blood vessels more dilated, or the surrounding tissue more hollow will make dark circles more visible.
Genetics and Skin Tone
Family history is one of the strongest predictors. If your parents have dark circles, you likely will too. A study of Malaysian Chinese adults identified specific gene variants linked to dark circles, including variations in the p53 gene and a gene involved in blood vessel growth (VEGFA). These findings suggest that both pigmentation patterns and vascular traits under the eyes are partly hardwired.
Darker skin tones are more prone to periorbital hyperpigmentation, the clinical term for dark circles caused by excess melanin. An Indian study found a prevalence of about 31%. People with more melanin-rich skin can develop concentrated pigment deposits around the eyes in response to friction, sun exposure, or even mild inflammation that wouldn’t leave a mark on lighter skin. This type of dark circle tends to look brown rather than blue or purple.
Allergies and Nasal Congestion
If your dark circles seem worse during allergy season, there’s a direct mechanical reason. When your nasal passages swell from allergies or chronic sinus congestion, the small veins that drain blood away from the under-eye area get backed up. Blood pools in those tiny vessels, creating a blue-gray to purple discoloration often called “allergic shiners.” This happens with both allergic and non-allergic rhinitis.
The effect goes beyond just visible veins. Repeated rubbing and itching of the eyes, common with allergies and eczema, triggers post-inflammatory hyperpigmentation. The skin responds to that chronic low-grade irritation by producing extra melanin, leaving behind darker patches even after the allergic episode resolves. Atopic dermatitis and allergic contact dermatitis around the eyes are well-documented triggers for this kind of lasting discoloration.
How Aging Changes the Under-Eye Area
Dark circles that worsen in your 30s and 40s are often structural rather than pigment-related. As you age, three things happen simultaneously around the eye socket: the fat pads that cushion the eye shrink and shift downward, the ligaments holding those fat pads weaken, and the bone of the upper jaw gradually resorbs. Together, these changes create a deepening groove between the lower eyelid and the cheek called the tear trough.
A prominent tear trough doesn’t change your skin color at all. It creates a shadow. Overhead lighting hits the protruding cheek and the lower eyelid differently, and the depression between them looks dark. This shadow-based dark circle is why some people notice their under-eye area looks worse in certain lighting or in photos but not others. It’s also why concealer alone often can’t fully correct age-related dark circles: you can’t conceal a shadow caused by lost volume the same way you’d cover a pigment stain.
Sleep, Dehydration, and Lifestyle Factors
Poor sleep doesn’t create dark circles from scratch, but it makes existing ones dramatically worse. When you’re sleep-deprived, blood vessels dilate and the skin can retain fluid, which together increase the contrast between the thin under-eye skin and the tissue beneath it. Your skin also looks paler overall when you’re tired, which makes the darker area under your eyes stand out more.
Dehydration has a similar effect. When your body is low on fluids, the skin around the eyes can look sunken and dull, exaggerating the hollowness that creates shadows. Alcohol and high-sodium diets contribute by disrupting fluid balance, sometimes causing puffiness that casts its own shadows, sometimes causing dehydration that makes the area look more hollow.
Screen time and eye strain don’t directly pigment the skin, but prolonged screen use increases blood flow to the muscles and vessels around the eyes, which can temporarily darken the appearance of the under-eye area in the same way that any increased blood pooling does.
Sun Exposure and Pigment Buildup
UV radiation stimulates melanin production everywhere, but the under-eye area is particularly vulnerable because the skin there is so thin and has less natural protection. Repeated sun exposure without sunscreen around the eyes leads to cumulative pigment deposits that darken over time. This is especially true for people with medium to dark skin tones who are already prone to melanin concentration in that area.
Wearing sunglasses and applying sunscreen to the orbital area can slow this process, though many people skip sunscreen near the eyes due to stinging. Mineral sunscreens with zinc oxide tend to be better tolerated close to the eye.
The Four Types of Dark Circles
Dermatologists generally classify dark circles into four categories based on their primary cause, because each one looks different and responds to different approaches:
- Pigmented: Brown or dark brown discoloration from excess melanin. Common in darker skin tones and worsened by sun exposure or chronic rubbing.
- Vascular: Blue, purple, or pink tones caused by visible blood vessels or blood pooling. Worsened by allergies, lack of sleep, and nasal congestion.
- Structural: Shadows caused by hollowing, fat pad loss, or tear trough deepening. Primarily age-related but can appear in younger people with naturally deep-set eyes.
- Mixed: A combination of two or three of the above, which is the most common presentation.
A simple way to check which type you have: gently stretch the skin under your eye in front of a mirror. If the dark color fades, it’s likely vascular (you’re dispersing the pooled blood). If it stays the same, excess pigment is more likely. If the darkness goes away when you tilt your face toward a light source, you’re dealing with a structural shadow.