Dark circles under the eyes rarely have a single cause. They result from a combination of genetics, skin structure, blood vessel visibility, and lifestyle factors that vary from person to person. Understanding which type you have is the first step toward knowing what might actually help.
The skin beneath your eyes is some of the thinnest on your body. That thinness means blood vessels, pigment changes, and volume loss in the area are all more visible than they would be elsewhere on your face. Most dark circles fall into one of a few overlapping categories: excess pigmentation, visible blood vessels, or structural shadowing from volume loss.
Genetics and Pigmentation
For many people, dark circles are simply inherited. Researchers have documented families where pigmentation around the eyes appeared in multiple members across six generations, with some mildly affected and others severely. Many of these individuals noticed the darkening early in childhood, and it deepened with age.
The genetic component often involves pigment-producing cells sitting deeper in the skin than usual, a condition called dermal melanocytosis. When pigment sits in the deeper skin layers rather than at the surface, it creates a distinctive grey or blue-grey tone under the eyes. This is different from surface-level pigmentation, which tends to look more brown. A dermatologist can distinguish between the two using a specialized light called a Wood’s lamp: surface pigment becomes more obvious under this light, while deeper pigment stays muted.
People with darker skin tones tend to have more melanin activity in the under-eye area, making pigment-driven circles more common. Sun exposure worsens this by triggering additional melanin production in skin that’s already prone to it.
Visible Blood Vessels
Some dark circles aren’t caused by pigment at all. They’re caused by blood vessels showing through thin skin. The under-eye area has a dense network of small veins, and when the overlying skin is particularly thin or pale, those vessels create a bluish or purple discoloration.
Anything that dilates those blood vessels or makes your skin paler will make this type worse. Sleep deprivation is a classic trigger. A study published in the journal Sleep found that sleep-deprived individuals were consistently rated as having darker circles under the eyes and paler skin compared to when they were well rested. The paler the skin becomes, the more the underlying vessels stand out. Researchers noted that blood flow to the skin increases during sleep, and disrupting that process likely contributes to the washed-out appearance that makes under-eye vessels so prominent.
Allergies and Nasal Congestion
If your dark circles get worse during allergy season, there’s a specific reason. Nasal congestion from hay fever or other allergies causes swelling in the tissue lining your nasal passages. That swelling physically slows blood flow through the veins around your sinuses, and those veins happen to run very close to the surface of the skin under your eyes. When blood pools in these congested veins, the area darkens and puffs up. The result, sometimes called “allergic shiners,” can look remarkably like a bruise.
This type of dark circle tends to come and go with your allergy symptoms. Managing the underlying congestion, whether through antihistamines or reducing allergen exposure, typically reduces the discoloration.
Volume Loss and Aging
As you age, the fat pads and bone structure around your eyes gradually change. The tear trough, a small depression that runs from the inner corner of your eye toward your cheekbone, becomes more pronounced as the face loses volume. This hollow sits directly below the lower eyelid and casts a shadow that reads as a dark circle, even when there’s no pigmentation or vascular issue at play.
The bone of the eye socket itself loses density over time, deepening the hollow further. Meanwhile, the ligaments supporting the mid-face loosen, and the fat pads in the cheek descend slightly. One researcher found that the junction between the thin eyelid skin and the thicker cheek skin doesn’t actually move much with age. Instead, the perceived worsening comes from volume changes in the surrounding tissue. The shadow simply gets deeper as the structural support around it diminishes.
This is why some people develop dark circles for the first time in their 30s or 40s despite never having pigmentation issues. The cause isn’t color, it’s geometry.
Anemia and Other Medical Causes
Iron deficiency anemia can make dark circles more noticeable, though it’s less common as a primary cause than many people assume. In one clinical study of 50 patients with under-eye darkening, only 10% had anemia and 12% had low vitamin B12 levels. The mechanism is straightforward: when hemoglobin is low, less oxygen reaches the small blood vessels under the eyes, and overall facial pallor makes the under-eye area look darker by contrast.
Thyroid disorders are sometimes mentioned as a cause, but the same study found no significant thyroid abnormalities among its participants. That said, if your dark circles appeared suddenly or are accompanied by fatigue, shortness of breath, or other systemic symptoms, a blood test can rule out nutritional deficiencies.
Contact Dermatitis and Skin Inflammation
Repeated irritation or allergic reactions in the under-eye skin can leave behind a type of pigmentation called postinflammatory hyperpigmentation. This happens when inflammation triggers excess melanin production, and the darkened skin persists long after the irritation resolves. Common culprits include eye makeup, skincare products, and chronic rubbing or scratching of the area (particularly in people with eczema or allergic contact dermatitis).
This type of darkening tends to be brownish and may affect one eye more than the other depending on which habits triggered it. Identifying and removing the irritant is essential, because continued inflammation keeps resetting the pigmentation cycle.
What Actually Helps
Because dark circles have different underlying mechanisms, no single treatment works for everyone. What helps depends on which type you have.
For vascular dark circles driven by visible blood vessels, topical products containing caffeine can temporarily constrict blood vessels and stimulate circulation in the area. Vitamin K, which strengthens capillary walls and reduces the visibility of blood vessels through thin skin, has also shown benefit. One clinical formulation using 3% caffeine and 1% vitamin K improved the appearance of dark circles in trial participants. These effects are modest and temporary, but they explain why many eye creams contain these ingredients.
For pigmentation-driven circles, sun protection is the most effective preventive measure. The under-eye skin responds readily to UV exposure, and daily sunscreen or sunglasses can prevent further darkening. Topical brightening agents that reduce melanin production can help over time, though deeper pigment embedded in the lower skin layers is harder to treat than surface-level discoloration.
For structural shadowing caused by volume loss, topical products have little effect because the problem is physical depth, not skin color. Dermal fillers injected into the tear trough are the most direct solution, restoring the volume that creates the shadow. The results are immediate but not permanent, typically lasting several months to over a year.
For allergy-related circles, treating the congestion is the treatment. Once blood flow normalizes through the periorbital veins, the discoloration fades on its own.
Sleep consistently makes a measurable difference regardless of the underlying type. While it won’t eliminate genetic pigmentation or structural hollows, adequate rest reduces the skin pallor and fluid changes that amplify every other cause.