Ask a Beauty Editor: Why You Should Never Use Expired Shampoo

Ever wanted to pick the brain of a beauty editor? Or get beauty product recommendations from someone who has tried them all? You've come to the right place. Beauty editor Hana Hong is here to answer your biggest skincare, haircare, and makeup questions, all submitted by Real Simple readers.

All beauty products expire. This is especially hard for people who have a tendency to hoard products to "save for later." But alas, all beauty products have a shelf-life, and your shampoo and conditioner are not immune.

Expiration Date Listing

Take it from two cosmetic chemists who make them. "Most shampoos will last for 18 months after being opened and will be marked with a PAO (period after opening) on the label," says Vince Spinnato, cosmetic chemist and founder of TurnKey Beauty Inc. "If the bottle has never been opened, it will expire three years from the date of purchase." Even the best shampoos will degrade in quality over time.

Some products will have a PAO number (period after opening) listed on the back, labeled as 12M, 18M, or 24M where M stands for months. This refers to shelf-life after opening. "If it's a true GMP-compliant [good manufacturing practices] facility making the product, this is something they test to ensure its efficacy after a certain period of time through an accelerated shelf-life testing process," says cosmetic chemist David Petrillo. "If it does not have a PAO, contact the company and see if you can reference a batch number to the product."

Visual Clues

But honestly? Most of us probably don't remember when we opened our shampoo. To tell if yours has expired, look for some visual clues. "The color, texture, and smell of a shampoo will change to the point that it doesn't look or smell right," says Spinnato.

As a rule of thumb, assume your shampoo is too old if it has an odd odor, looks clumpy, has changed color, or doesn't seem to be lathering as it once did.

If you're tempted to use it anyway, hear us out. Expired shampoo isn't effective, which can result in your hair looking dull and dirty. And even worse? Because the preservatives have probably lost their potency, the product is no longer stable. The shampoo's chemical change can cause itching or irritation to your scalp. After that, mold and bacteria begin to grow, potentially triggering bacterial breakouts or fungal diseases on the scalp.

"There are many things that can happen when a product expires," says Petrillo. "Many times the chemical components can separate, giving the product a clumpy, unnatural appearance. It can potentially be harmful as the ingredients were not meant to be applied in this manner or penetrate the skin separated. Even though the shampoo does not stay on the hair as long, the ingredients still penetrate the outer layers of skin on the scalp."

The bottom line: If you've been experiencing issues like dandruff, itchy scalp, overly greasy hair, or hair loss, consider your shampoo's age first before taking any extreme measures. Is it past its expiration date? Please just throw it out.