It is common to notice a small, dark spot suddenly appear on the lip and wonder if it is the same kind of freckle that forms on the skin. Pigmentation changes on the lips are a frequent dermatological concern, and while they may resemble a common freckle, their underlying biology is often distinct due to the lip’s unique mucosal tissue environment.
Understanding Lip Spots vs. Skin Freckles
The typical freckle found on sun-exposed skin, known medically as an ephelis, is a flat, light brown spot caused by the increased production of the pigment melanin within the skin cells. A defining characteristic of a true freckle is that it tends to darken significantly with sun exposure and often fades or disappears almost entirely during the winter months when ultraviolet (UV) light is less intense. This dynamic response to sun exposure is a hallmark of ephelides.
The spots that appear on the lip’s vermilion border, however, are usually classified differently, most often as a labial melanotic macule. This type of spot is a benign, flat patch of hyperpigmentation. It occurs because the pigment-producing cells, called melanocytes, are functionally hyperactive and produce more melanin than usual. While they may appear similar to a freckle, melanotic macules are persistent and do not fade with the seasons, remaining present year-round.
Another possible diagnosis for a lip spot is a solar lentigo. This is also a flat, dark spot, but it is caused by an increase in the number of melanocytes, not just an increase in their activity. Solar lentigines, like melanotic macules, are persistent, unlike the temporary nature of true freckles. Both conditions are harmless, but the distinction lies in whether the melanocytes have multiplied or are simply producing more pigment.
Primary Causes of Lip Hyperpigmentation
The most recognized factor contributing to the formation of a melanotic macule on the lip is chronic exposure to ultraviolet radiation. Although the lips are often overlooked in sun protection routines, UV radiation can stimulate the pigment-producing cells in the lip tissue. This leads to an overproduction of melanin in a localized area, which is implicated in the development of many labial melanotic macules, particularly on the lower lip.
Physical damage or irritation to the lip can also trigger a temporary form of darkening known as post-inflammatory hyperpigmentation. Actions like lip biting, persistent licking, or trauma can cause inflammation, which results in the deposition of excess melanin pigment as the tissue heals. This type of hyperpigmentation fades slowly over time once the source of irritation is removed.
Less common contributors to lip darkening include certain systemic conditions or medications. Hormonal fluctuations, such as those during pregnancy, can lead to increased pigmentation on the lips, similar to melasma on the face. Furthermore, some drugs, including certain antibiotics and anti-malarial medications, are known to cause drug-induced pigmentation that can manifest as dark spots on the labial mucosa.
When to Consult a Dermatologist
While the vast majority of lip spots are benign conditions like melanotic macules, any new or changing spot requires professional evaluation to rule out more serious possibilities, such as melanoma. A checkup is important because mucosal melanoma, though rare, can sometimes mimic the appearance of a benign spot in its early stages. A dermatologist will assess the spot clinically and may use a handheld magnification device called a dermatoscope for a closer look.
The standard warning signs for skin cancer, often summarized by the ABCDE criteria, are adapted for use on lip lesions to help identify potential malignancy. These criteria include Asymmetry, where one half of the spot does not match the other, and an irregular Border that is notched or blurred. Color variation within the spot, such as shades of brown, black, or even blue, is also a concerning sign.
The last two letters, Diameter and Evolution, are particularly relevant. Any spot larger than a pencil eraser (about 6 millimeters) or one that is Evolving—changing rapidly in size, shape, or color—should be checked immediately. New symptoms like bleeding, crusting, or a raised, nodular texture are urgent indicators for a professional biopsy. If any doubt exists about the nature of the spot, a biopsy is recommended for a definitive diagnosis.