As of 2015, there is little concrete evidence to support the claim that apple cider vinegar promotes hair growth. However, a number of sources with dubious medical reputations, such as AppleCiderVinegarHub.com and NiceHair.org, do make the claim that vinegar can reverse hair loss when ingested or rubbed into the scalp.
According to WebMD, some natural remedies that may have more promising results than apple cider vinegar include reducing stress, eating a diet rich in iron and zinc, and cutting back of harsh styling treatments such as perms. However, applying apple cider vinegar to the hair is not without benefits. Mixing it with shampoo tends to make hair softer and more manageable.