How can you tell when a disinfectant is no longer effective?

• A. Its color changes to a darker hue.
• B. The bottle smells different.
• C. Expiration date passed, product changes color/consistency, or label indicates expired.
• D. The product becomes more expensive.

Answer: (C)

Disinfectant potency depends on the stability of its active ingredients, which can degrade over time. The most reliable signal that a product is no longer effective is the expiration date on the label; once that date has passed, the manufacturer can no longer guarantee disinfection performance. In addition, visible changes in color or consistency can indicate chemical changes, separation, or contamination that reduce effectiveness, so if you notice those changes, the product should not be trusted. Some labels also plainly indicate that the product is expired, which is another clear sign to discard it. In contrast, a change in smell or a higher price doesn’t reliably reflect whether the disinfectant will work, and a color change by itself isn’t enough to determine potency. Keep to shelf-life guidelines, store as directed, and replace products when they’re expired or show concerning changes.