Do whatever you can to prevent a bee from stinging your cat. But life happens and if your cat gets stung in her mouth, there is a very high risk of severe swelling, which can result in difficulty breathing.
Also, if she gets stung by multiple bees, she may develop a fatal anaphylactic reaction, so it is advisable to take your cat to the vet as soon as possible after the stinging incident.
There are no over-the-counter medications that will work in these situations, and the medication will need to be given intravenously, which can only be done by a veterinarian. Her mouth will be very sore, so you will not be able to administer medication orally.
Dr Vanessa McClure, veterinarian