Mayonnaise does not make hair grow faster. However, when applied correctly, it can act as a cheap deep conditioning treatment for individuals with coarse, thick or very dry hair.
Mayonnaise contains eggs, oil and vinegar. The eggs in mayonnaise help add protein to the hair, while the oil helps add moisture and deep shine. Vinegar helps restore proper pH levels to the hair, according to Naturally Curly. Woman's Day recommends massaging a tablespoon of mayonnaise through clean, damp hair. Allow the mayonnaise to sit for 30 minutes, and rinse with cool water and a cleansing shampoo. Individuals with fine hair should use mayonnaise sparingly to avoid greasy hair.