The vast majority of hair-color products at the drugstore are permanent colorants. They all work the same way with similar ingredients; all contain ammonia and peroxide, which open up the hair follicle so it can be colored. Choosing the right product is mostly a matter of color selection and ease of use.
L'Oréal Paris Superior Preference (Est. $9) is an old favorite among many users at TotalBeauty.com and Walmart.com. Many say they have been using the formula for years and are still happy with the natural-looking results. Superior Preference comes with a classic squeeze tube applicator that most say is easy to use. The tube has an extended tip, which makes it easy to reach roots, according to editors at Allure magazine. It comes in 51 shades, which reviewers say are vibrant, glossy and last for weeks -- up to eight -- without fading.
Users have mixed opinions about how well the formula covers gray, but that may be due to the specific color choice and/or how long the dye was left on the hair. It's important to note that the formula has an ammonia base, which allows for more dramatic color change, but it can have a strong odor.
If you prefer a less obnoxious scent from an ammonia-free hair color, Revlon ColorSilk (Est. $3.50) is a great alternative. The formula relies on lauramide MEA to change hair color rather than ammonia. Technically, that makes the formula demi-permanent (even though manufacturers call it "permanent") according to cosmetic chemists at TheBeautyBrains.com. The formula still changes hair color permanently, but it isn't capable of the dramatic changes that ammonia-based formulas like Superior Preference afford. Still, Revlon ColorSilk remains popular with beauty magazines and users alike.
Testers at Good Housekeeping praise ColorSilk for its ability to immediately cover gray hair and for producing long-lasting, fade-resistant color. Editors say the color was especially vibrant in the blonde and brunette shades. Users at MakeupAlley.com agree, giving the formula an overall rating of 3.9 out of 5 stars based on more than 650 reviews. That said, L'Oréal Paris Superior Preference is our Best Reviewed pick because it's chosen more often in professional tests and is able to make more dramatic changes to hair color.
All permanent hair colors use a process that involves bleaching or lifting the current color and then adding the color that you want, all of which can dry and damage your hair. For this reason, experts suggest conditioning your hair after every shampoo and doing a deep condition once a week.