Aspirin (acetylsalicylic acid) is a widely used over-the-counter nonsteroidal anti-inflammatory drug (NSAID). It is commonly taken to relieve pain, reduce fever, and decrease inflammation. Given its widespread use, some people search for unusual effects, such as the claim that aspirin might alter eye color. This article investigates whether this common medication can truly change a person’s eye color.
The Direct Answer: Aspirin and Eye Color
The straightforward answer is that aspirin does not change the color of a person’s eyes, and there is no scientific evidence to support this claim. Eye color is determined by the pigment in the iris and is fixed in adulthood. The pigmentation of the iris is remarkably stable once it matures, usually after early childhood.
Perceived shifts in eye shade are usually an illusion caused by factors like changes in lighting, background colors, or pupil dilation. When the pupil constricts, the colored part of the iris can appear more intense. These are temporary visual effects and do not represent a permanent biological change to the iris pigment itself.
Actual, lasting changes in eye color are extremely rare and typically signal a medical issue, such as injury or specific eye diseases. Conditions like Fuch’s heterochromic iridocyclitis or pigmentary glaucoma can cause visible changes due to inflammation or pigment loss. Certain prescription eye drops, such as prostaglandin analogs used for glaucoma, can cause eyes to permanently darken by stimulating melanin production, but aspirin lacks this effect.
The Biology of Eye Color Determination
Eye color is a complex, polygenic trait determined by the amount and distribution of melanin within the iris stroma. Melanin is produced by specialized cells called melanocytes in the anterior layer of the iris. The color perceived depends on how light interacts with the melanin content, not on the presence of blue, green, or hazel pigments.
Brown eyes contain high concentrations of the dark pigment eumelanin, which absorbs most light. Blue eyes contain very low amounts of melanin, allowing light to scatter as it passes through the tissue (Rayleigh scattering). This scattering preferentially reflects shorter, blue wavelengths of light, making the eyes appear blue.
Green and hazel eyes result from intermediate melanin levels, often combined with pheomelanin and the same light-scattering effect. Genes like OCA2 and HERC2 regulate melanin production and establish eye color early in life. Aspirin does not possess the biological mechanism required to alter this genetically determined pigmentation structure.
Aspirin’s Actual Mechanism and Systemic Effects
Aspirin’s therapeutic effects stem from its unique mechanism of action as an NSAID and an antiplatelet agent. It works by irreversibly inhibiting the cyclooxygenase (COX) enzymes, specifically COX-1 and COX-2, throughout the body. The aspirin molecule acts as an acetylating agent, covalently attaching an acetyl group to a serine residue in the active site of the enzyme.
This irreversible blockade prevents the COX enzymes from producing prostanoids, which are signaling molecules that include prostaglandins and thromboxane A2 (TXA2). By inhibiting prostaglandin production, aspirin reduces the sensation of pain and fever. Its antiplatelet effect is particularly important, as the blockade of TXA2 in platelets inhibits their aggregation. This is why low-dose aspirin is used to reduce the risk of heart attacks and strokes.
While aspirin does not affect eye color, it does have documented systemic effects and potential side effects, primarily related to its COX inhibition. The most common adverse effects involve the gastrointestinal system, including irritation, ulcers, and an increased risk of stomach bleeding. The blood-thinning property that benefits cardiovascular health also increases the general risk of bleeding. Furthermore, some studies have suggested an association between long-term regular aspirin use and an increased risk of developing age-related macular degeneration (AMD).