If you've developed severely irritated and chapped lips or a rash around your mouth, and you think your toothpaste is to blame, the first thing to do is stop using that toothpaste. You can try switching to a new variety or brand and see if your symptoms resolve.
It's also a good idea to see your dentist or doctor. A medical professional can perform an allergy test to determine if you're allergic to the toothpaste. If the ingredients in the toothpaste are known, your doctor or dentist can test individual ingredients to further narrow down your toothpaste allergy. As the review published in Dermatitis noted, it's important to run a second test if the first one confirms an allergy to the toothpaste. That way, you can identify the specific allergen and learn to avoid it in the future.
A toothpaste allergy doesn't have to get in the way of having great oral hygiene. Once you know what you're allergic to, you know what to look for – and what to avoid – when you're browsing the oral care aisle.