Yes, shampoo does expire, although it's not always clearly indicated on the bottle. While not all shampoos have an explicit expiration date, they do have a shelf life. The length of time a shampoo remains effective depends on whether it's opened or unopened and how it's stored.
Shelf Life of Shampoo
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Unopened Shampoo: An unopened bottle of shampoo can last for 2-4 years if stored properly in a cool, dry place, away from direct sunlight and extreme temperatures. Several sources confirm this timeframe. [1, 5, 9, 10]
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Opened Shampoo: Once opened, shampoo's shelf life significantly reduces. Most shampoos will last for 6 months to a year, or even up to 18 months, after opening. [1, 4, 7] Look for a PAO (Period After Opening) symbol on the packaging, commonly represented as 6M, 12M, 18M, or 24M, indicating the number of months after opening the product is usable. [1, 4]
Signs of Expired Shampoo
While an expiration date isn't always printed, there are visual and textural cues to look for:
- Changes in Consistency: Separation of ingredients, unusual thickening, or thinning of the shampoo are signs of spoilage. [2]
- Unusual Smell: A rancid or unpleasant odor indicates that the shampoo has gone bad and should be discarded. [2]
Using Expired Shampoo
Using expired shampoo likely won't cause severe harm; however, it might not clean your hair effectively and could potentially irritate your scalp. [2, 8] It's best to discard shampoo that shows signs of spoilage or has exceeded its recommended shelf life. [7]
