A compound that acts as a strong, caustic base. It is occasionally used in personal lubricant production to control acidity. Sodium hydroxide is sometimes listed as NaOH, lye, or caustic soda.

In its raw form, sodium hydroxide can cause serious chemical burns when it contacts skin. However, it is highly diluted when used in personal lubricants and is considered a safe ingredient. It may cause irritation for some users depending on the formula of the lubricant.