Technically, Epsom salts do not expire in a way that makes them dangerous. They are a mineral compound—magnesium sulfate—and minerals don’t rot. Think of them like table salt or sugar left in your pantry.
However, just because they don’t spoil doesn’t mean they stay perfect forever. It’s like that old sweater you love; it still works, but it might look a bit faded. Over time, your Epsom salts can absorb moisture from the air, turning from fluffy crystals into a sad, solid brick.
