The appearance of the nipple and the surrounding areola (the nipple-areola complex) varies widely among individuals. These tissues range in color from pale pink to dark brown, determined primarily by the concentration of the pigment melanin. A change in color on just one side is noticeable, and while many causes are benign, any unilateral alteration warrants attention.
Hormonal Shifts and Natural Changes
The most common drivers of color changes in the nipple-areola complex are fluctuations in hormone levels, particularly estrogen and progesterone. These hormones influence melanocytes, the cells responsible for producing melanin, stimulating them to increase pigment production. While this process typically results in bilateral darkening, subtle asymmetries in localized receptor sensitivity can sometimes make the change more noticeable on one side.
During puberty, rising estrogen levels initiate breast development, leading to a noticeable darkening of the nipple and areola. The menstrual cycle also involves continuous hormonal shifts; some individuals experience temporary darkening (catamenial hyperpigmentation) just before or during menstruation due to peak estrogen levels. This transient darkening usually fades after the period ends.
Pregnancy is a period of significant change, marked by elevated levels of estrogen, progesterone, and melanocyte-stimulating hormone. This hormonal combination causes hyperpigmentation across the body, often making the areola larger and substantially darker. Hormonal contraceptives, which introduce synthetic hormones, can similarly trigger an increase in melanin and cause a darkening effect.
External Irritation and Dermatological Issues
When a color change is observed only on one nipple, localized external factors or skin conditions are often responsible. The areola skin is delicate and susceptible to contact dermatitis, an inflammatory reaction caused by direct exposure to an irritant or allergen. Common culprits include new laundry detergents, body washes, or topical lotions applied to the chest area.
This reaction manifests as an itchy, red, or discolored rash that may involve scaling or crusting, altering the perceived color. Friction is another frequent cause of unilateral alteration, often from a poorly fitting or rough-textured bra. Constant rubbing causes localized inflammation, potentially leading to post-inflammatory hyperpigmentation or a persistent reddish hue on the affected side.
Inflammatory skin disorders such as eczema or psoriasis can also affect the nipple and areola, causing patches of dry, scaly, discolored skin. Eczema damages the skin barrier, leading to redness and flaking that alters the perceived color. Since these conditions do not always affect both sides equally, they can account for a color change observed on a single nipple. Localized fungal or yeast infections are less common but can also cause a red, shiny rash.
Indicators of Serious Medical Conditions
While most color changes are benign, certain rare but serious medical conditions can present initially as a unilateral change, often accompanied by other specific symptoms. Paget’s disease of the breast is a rare cancer that begins in the milk ducts and spreads to the skin of the nipple and areola. This condition typically affects only one breast and often mimics a persistent dermatological issue like eczema.
A primary indicator of Paget’s disease is a scaly, red, or crusty patch that starts on the nipple and spreads to the areola, often accompanied by itching, burning, or discharge. Unlike common eczema, Paget’s lesions are typically persistent and fail to heal. The condition may also cause the nipple to flatten or turn inward (inversion), or a lump may be palpable behind the nipple.
Inflammatory breast cancer (IBC) is another aggressive malignancy that causes rapid changes in the appearance of the breast skin. While IBC may not directly change the nipple color, it can cause the skin to appear red, thickened, or pitted, sometimes described as having an “orange peel” texture. The resulting inflammation and redness across the breast can make the nipple area look significantly discolored and swollen on the affected side. Localized infections like mastitis can also occur in non-lactating individuals, causing a painful, red, and warm area that changes the skin color.
When to Consult a Healthcare Provider
Any new or persistent change in the color or texture of a single nipple warrants a medical evaluation to rule out less common causes. It is important to seek prompt attention if the color change is accompanied by specific concerning symptoms.
Concerning Symptoms
Immediate consultation is necessary if the skin change involves crusting, flaking, or scaling that does not resolve within a few weeks. Other concerning signs include:
- The development of a firm, fixed lump in the breast tissue or under the arm.
- Any abnormal discharge from the nipple, especially if it is bloody or occurs spontaneously from only one duct.
- The sudden development of a retracted or inverted nipple.
- Skin thickening and persistent redness that covers a large portion of the breast.