Maybe you only shampoo and condition your hair once a week, or perhaps you rotate through many different products. In either case, a bottle of shampoo or conditioner may last you a really long time. This can be great in some ways, but it also raises one big question that many people never really think about: Do shampoo and conditioner expire? It turns out that yes, shampoo and conditioner both expire, and when they do, it’s not a great idea to use either product. Ahead, a dermatologist and a cosmetic chemist explain all you need to know about shampoo and conditioner expiration, including signs of when to toss your bottle.

Do Shampoo and Conditioner Expire?

The answer here is simple: Yes, shampoo and conditioner can both expire. This means you should be on the lookout for the product’s expiration date and any signs that it may have passed its prime. Typically, the expiration date is listed on the bottle or somewhere on the packaging—you may need to look at the box it came in. If you can’t find that information, try getting in touch with the company who made the product. “It would be a good idea to reach out to the manufacturer to get some additional information on batch identification or when it expires,” says cosmetic skincare chemist David Petrillo. “If they are unable to identify the product, then it may be a good idea to return the product or throw it away.”

How Long Do Shampoo and Conditioner Last Before Expiring?

Most shampoo and conditioner lasts at least six months or longer, though the specifics vary from one product to the next. An open bottle of shampoo or conditioner usually lasts between six months and a year, Petrillo says—but if the bottle hasn’t been opened, it may last up to two or three years. “You will want to look for a PAO (period after opening) date, which is usually labeled as 6M, 12M, 18M, or 24M,” Petrillo says. “The M stands for months, and this should tell you how long the product is good for after you’ve opened it, as long as it’s stored in proper conditions.

Is Okay to Use Expired Shampoo?

When shampoo and conditioner expire, they can become unstable, so you shouldn’t use them. The product may not only lose its effectiveness, but it could also irritate your skin or be harmful in other ways. “If the product is expired, chances are it is very unstable and ingredients are separated with potential bacteria contamination, which can lead to irritation, dryness, peeling, damage to follicles, and possible hair loss, to name a few,” Petrillo says.

Rarely, the degraded or unstable ingredients in expired shampoo and conditioner can cause a rash. “Sometimes, when the formula is no longer stable, it can grow mold too,” says board-certified dermatologist David Kim, MD.The rash is often in the form of contact dermatitis, which is an itchy, painful, or swollen rash that appears when someone comes into contact with something they’re allergic to or that irritates their skin.

The main reason to avoid expired shampoo and conditioner is so that you’re not in contact with the product’s ingredients, which may no longer be stable. “It is never a good idea to use expired shampoo or conditioner, as it can be harmful to apply when the ingredients have been separated and the preservatives are no longer effective,” Petrillo says. “There could be potential contamination and harmful microorganisms [that] have developed that you do not want absorbed into your hair or scalp.” Shampoo and conditioner ingredients can penetrate your scalp fairly quickly, so expired shampoo or conditioner can have negative side effects even if they’re only applied briefly.

Signs of Expiration in Shampoo or Conditioner

One way to tell if your shampoo or conditioner has expired is to check the expiration date listed on the package. “The bottle usually has a ‘period after opening’ logo, which is a logo that looks like a tiny container or jar with a number,” Kim says. “If it says 24M, it means the product is good for 24 months after opening.” You can also keep an eye out for physical changes to the product, as your shampoo or conditioner may have expired if the product is clumpy, separating, or the color has changed. Here are some specific signs of expiration that Petrillo recommends looking out for:

• Separating ingredients: “This means some of the chemical components have separated,” Petrillo says. “When this happens, you will usually see chemicals separated into layers, such as the oil components at the top and water components in a separate layer.” If you pour out some of the shampoo or conditioner, you’ll probably notice the separating ingredients right away.
• Changes in texture or color: This sign of expired shampoo or conditioner will most likely appear off or unnatural-looking, such as a clumpy texture or a new color. “The preservatives are most likely not effective and the product is no longer stable, so you may notice color change or discoloration,” Petrillo says.
• Unpleasant smell: “If you notice a bad smell or unnatural odor to the product, this is something you may want to confirm with the brand or manufacturer,” Petrillo says.

If the shampoo or conditioner’s consistency seems off (such as when the product is separating), you may be tempted to shake the bottle to mix the ingredients back together, but that’s actually not a great idea. It won’t mix well or maintain the same consistency it had when manufactured, and it also probably won’t penetrate the scalp the way it’s intended to, Petrillo says.

The Final Takeaway

Shampoo and conditioner can both expire, and when they do, you should avoid using them. Expired shampoo and conditioner can be harmful to your health, and they also may no longer be effective. Once open, most shampoo and conditioner lasts between six months and a year, but unopened bottles can last longer. To avoid wasting product, make note of the packaging’s period after opening date upon first purchase, and do your best to use all of the shampoo or conditioner by that time.