Does Hair Oil Expire? Signs It’s Gone Bad and How to Store It

You probably check the expiration dates on any food in your fridge, but can you say the same about the hair care products in your medicine cabinet?

Here’s the thing: All beauty and styling products expire, including hair oil, and it’s important to recognize the signs that a hair care product has gone bad.

Here, we’ll cover how long hair oil lasts, signs that it’s gone bad, and how to store it so it stays fresh for as long as possible.

Hair oil is a beauty product that can tame frizz and add moisture and shine to hair. It’s usually made of a blend of natural oils (like argan, coconut, castor, jojoba, or olive oil), plus essential oils for scent and other ingredients like preservatives.

Some hair oils, like tea tree oil, can help with issues like dandruff, while others may be part of a hair care routine meant to support hair growth.

Here’s the tricky thing about expiration dates on beauty products: Unlike most foods, which expire on a certain date regardless of whether they’ve been opened, the expiry date of cosmetic products largely depends on when you open them.

If you look at your bottle of hair oil (or any cosmetic product), you’ll see a small open jar symbol with a number and the letter M printed inside the jar. This symbol is known as the period after opening (PAO) label, and it indicates how long a product will stay good after it’s been opened. The M stands for months, so if it says 9M, the product will be good for nine months after opening. This should be printed on the outer packaging as well as on the product itself.

Generally, hair oil has a PAO of nine months to a year, meaning it lasts about nine months to a year after opening it, but it’s always best to check your specific bottle. This timeframe will vary depending on the ingredients used in the product.

Products may have a slightly longer shelf life than the POA (meaning if something has a nine-month period after opening, it’s not going to be rancid on the first day of that ninth month), but it’s a good guideline to follow to ensure the product works its best.

Unopened hair oil tends to last one to three years, depending on its exact ingredients. For example, research shows that cosmetic argan oil can be preserved for about one year.

Why Does Hair Oil Go Bad?

Hair oil typically goes bad due to oxidation, a process in which certain ingredients react with air, light, and moisture (the same for all beauty products and cooking oil).

This is why the expiration countdown begins after opening — once exposed to oxygen, the product becomes less stable, eventually reducing its effectiveness or making it unsafe to use.

Nothing terrible will happen if you use expired hair oil (especially if it’s recently expired).

However, expired products typically don’t work as well. According to the American Academy of Dermatology (AAD), old cosmetics may cause skin problems or not perform as well. This statement is about makeup, but the same applies to hair products.

Most likely, the product will smell weird and the scent will transfer to your hair, it may not work as intended, and/or it could potentially cause scalp irritation.

The tricky thing about products that have PAO labels is that you have to remember when you opened the product. You may want to write down the date in permanent marker right on the bottle. But if you’re not sure if a product is expired, there are few things you can do.

• Smell it. If it smells rancid or off, it's likely oxidized.

• Look at the texture. Hair oil that feels sticky or thick is likely no longer good.

• Check for color change. If the oil darkens or turns cloudy, it may no longer be stable.

• Look for separation. According to the FDA, if the product is an emulsion (a mix of water and oil) separation can indicate that the product has broken down or degraded.

• Notice irritation. If it causes itching or irritation to the scalp when applied, it’s best to discard it (and consult a dermatologist if the irritation persists).

To help your hair oil last as long as possible, store it in a cool, dark environment (like inside a medicine cabinet or in a drawer). Keep it out of direct sunlight and high temperatures (UV rays are a major cause of oxidation).

If the hair oil bottle is designed so it comes into contact with your palm as you dispense the product, make sure to always wash your hands before using it to avoid transferring bacteria from your hands to the product. Always make sure the cap is on tight.

Looking for the abridged version? Here’s what to remember about whether hair oil expires.

Like all hair care products, hair oil expires. Look for the “open jar symbol,” which looks like a cosmetics pot with a jar lid and has a number followed by the letter M written inside. This is known as the “period after opening” (PAO), which tells you how many months the product is good for once it’s been opened.

• If you’re unsure how long you’ve had your hair oil, check for signs that it has turned bad. Expired hair products may have a rancid or strange smell, separation of the ingredients, and a cloudy or dark appearance. If your scalp feels irritated, discontinue use immediately and contact your dermatologist or other healthcare provider.

• To keep your hair oil fresh, store it in a cool, dark place, and make sure the cap is tightly sealed.

If you have any more questions on hair products or expiration dates, check out our guides to minoxidil expiration and pomade and hair loss. Or do a deep dive on all our guides to oils for hair growth.