What is the active ingredient commonly found in nail bleach or whiteners?

The active ingredient commonly found in nail bleach or whiteners is hydrogen peroxide. This compound is known for its bleaching and whitening properties, which effectively lighten the natural color of nails and remove stains. In the context of nail care, hydrogen peroxide acts as an oxidizing agent that can penetrate the nail surface, helping to break down discolorations and yellowing caused by various factors such as nail polish or environmental exposure.

While ammonium hydroxide, acetic acid, and calcium carbonate have applications in other areas (like cleaning agents or as a mild abrasive), they do not possess the same bleaching capability specifically for nails as hydrogen peroxide does. Therefore, when considering nail whiteners, hydrogen peroxide stands out as the primary and most effective active ingredient for achieving a brighter and whiter appearance.