How do you tell if a bath bomb is expired?

Do Bath Bombs Expire?

Bath bombs have a shelf life of about one year. A bath bomb will last only as long as its composite ingredient with the least shelf life. It is true that a bath bomb has a scent as sweet as an air freshener, but if it does expire, it will start to its scents as well as its good looks and effect.
If your bath bomb starts to smell bad, break up or grow mold, it is a sign that it has expired, and you should learn to throw them out at this point.

How can you tell if a bath bomb has expired?

Smells: Old bath bombs that have passed their expiration date might begin to have a chemical smell or have that rancid smell. If it has a weird smell different from its natural fragrance, then you should halt using it.
No Fizz: An old bath bomb will lose its fizz as its ingredients like baking soda and citric acid constantly lose a bit of their effectiveness as time passes and would not have the same reaction. The constituents mentioned are the real reason a bath bomb fizzes. If your bath bomb doesn't have any fizz in it, it is likely that it doesn't work as well as it should. So, don't use it to avoid being disappointed.
Discoloration: With time, bath bombs are known to change their shade or fade in color. The more faded your bath bomb looks, the more you are certain it has gone past its expiry date. It is important to note that you should not use a bath bomb that has really faded as it can irritate your skin.
Mold: Can mold grow on bath bombs? The short answer is yes. Mold growing on your bath bomb is a great sign that it is way over its expiry date. Most people don't know that it is dangerous to use bath bombs with mold on them. Bath bombs with natural ingredients like milk, butter, and oatmeal are more likely to be moldy. This can also happen if your bath bomb has been exposed to oxygen, mold spores, or water.