What causes nails to turn yellow after applying nail polish?

Fingernails and toenails protect you during daily activities like walking and handling objects, and they’re perfect for relieving itches. Since nails reflect your health and appearance, people often notice well-maintained nails positively or react negatively to unhealthy ones. Driven by both vanity and hygiene, Americans invest billions annually in nail care products and services [source: Carlson, Eisenstat and Ziporyn].

Nails are composed of dense, hardened layers of epidermis cells, identical to those forming your skin. These cells are dead and rich in a protein known as keratin. Only 75% of the nail bed, where the skin is still connected, is visible above the surface. A full nail takes approximately six months to grow, with men’s nails growing faster than women’s.

Similar to skin, nails require oxygen to remain healthy. The keratin in nails also permits water to pass through them. Issues like ridges, peeling, brittleness, or discoloration may signal underlying health problems. Yellow nails can point to psoriasis, fungal infections, pulmonary diseases, or smoking. Often, however, yellowing is simply due to staining from foods or chemicals, such as those found in nail polish.

What's in nail polish?

Nail polish, also known as nail enamel or lacquer, has advanced over centuries due to scientific innovation. Modern nail polishes are generally safe, containing chemicals designed to enhance application, drying, shine, and durability on the nail.

Here are the key ingredients commonly found in nail polish today:

In recent years, water-based nail polishes have emerged in the market. These polishes still require a film-forming agent, solvent, and pigment, but they aim to eliminate petrochemical solvents. The new formula targets consumers with ingredient sensitivities or those seeking eco-friendly cosmetic options.

In the U.S., all nail polish colors must be FDA-approved. The hues are created using a mix of organic dyes and other materials, such as iron and chromium oxides for red and yellow, and ultramarine for blue. Titanium dioxide is used in creamy polishes for opacity, while pearlized polishes contain natural pearl (guanine crystals) or the more affordable bismuth oxychloride.

Protect Nails from Yellowing

As previously noted, yellow nails can stem from various causes, including medical conditions. However, when related to nail polish, the yellowing occurs as nails absorb pigments from the polish. Red shades, ranging from light pink to deep burgundy, dominate the U.S. nail polish market, with darker reds being the most likely to cause yellow staining.

Let’s examine iron oxides, a family of pigments, more closely. These chemicals, often referred to as 'rust' when found on cars or old metal pipes, are commonly used by paint and nail polish manufacturers as red and yellow pigments.

If you’ve lived in an older home, you might have noticed brown water from rusty iron pipes, which can stain porous porcelain sinks with reddish-brown marks from iron oxides. Similarly, iron oxides in nail polish are suspended in a different solution. Since keratin in nails can absorb liquids, nails may also absorb these pigments, leading to yellowish or brownish stains that linger even after polish removal.

Can a base coat help? The main purpose of a clear base coat is to create a smooth surface for applying colored polish. Some base coats are thick enough to act as a full first layer, potentially reducing or preventing yellowing caused by direct contact between the nail and pigments.

Is nail polish remover a concern? While the remover itself is volatile and can harm the skin with excessive use, it’s unlikely to cause yellowing directly. However, as a strong solvent, it may increase nail exposure to polish pigments. To minimize this, replace cotton balls or applicators frequently during polish removal.

For more insights on nail polish and nail care, grab your coat and explore the next page.