Treating Venomous Insect Stings in Cats Leave a comment

By Dr. Hanie Elfenbein, DVM

Cats are inquisitive creatures. Unfortunately, that sometimes get them into trouble — like when they mess with the wrong bug.

Allergic Reactions to Insect Bites and Stings

Depending on where you live, your cat is at risk from different types of insects. Keeping them indoors helps to reduce the risk, but won’t eliminate it. Insects can get into your house through doors, windows, or even make their way through cracks in the wall. And if you also have a dog, you and your dog can bring bugs (like ticks) with you into the house.

Some insects have venom that is transmitted via a bite or sting, while others do not have venom but can still cause an allergic reaction.

Venoms work in different ways, but they are all meant to serve as a deterrent to mammals. In the United States, a single bite or sting is very unlikely to kill a healthy adult cat. However, when insects swarm, such as yellow jackets or ants, the cumulative effect can cause severe reactions in cats that require emergency treatment. 

Some cats may be allergic to either the bite or to the venom of an insect. Allergic reactions can range from minor swelling at the injury site, to hives and anaphylaxis. Anaphylaxis is when the throat swells and the cat has difficulty breathing. It may cause vomiting, diarrhea, and collapse. Anaphylaxis is always an emergency.

A minor allergic reaction can often be effectively treated with a cold compress and diphenhydramine (Benadryl) at 1mg per pound of cat. For most cats, that’s about 1/4 to 1/2 of a 25mg tablet given by mouth. [Check with your cat’s doctor before administering any over the counter medication, as your cat may have other conditions that can be worsened by the diphenhydramine, may be on other medications that should not interact with the drug, or the cat’s age will determine treatment and drug of choice.] Topical treatment is not recommended because the cat may ingest it [through self-grooming].

If the swelling persists, your cat appears painful or is not behaving normally, or if you have any concerns, it is always best to see your veterinarian or go to the closest 24-hour clinic.

Insects and Arachnids That Bite


Many types of ants bite. Some, but not all, biting ants are venomous.

The main ant of concern in the United States is the fire ant. These ants are not native to the United States but have become increasingly common in the Southern and Gulf states since the late 1930s or early 1940s. The bite of the fire ant is painful but not toxic — the toxin comes after the bite. Fire ants bite to grip the skin of the victim, and then use their stinger to inject a toxic alkaloid venom, Solenopsin. They tend to swarm when their nests are disturbed.

Bees and Wasps

Bees produce melittin, a mild venom that causes pain but is only a real concern if your pet is allergic or is stung by multiple bees. Bees leave their stinger in the victim. If you are able to remove the stinger from your cat, that may help reduce the pain. If not, your veterinarian can remove the stinger for you.

Wasps, yellow jackets, and hornets produce a stronger venom that contains enzymes which can cause cellular death in the region of the sting. They do not lose their stinger in the skin, allowing them to sting multiple times.


Flea reactions are probably the most common bug-related complaint that brings cats to clinics. Some cats get very itchy from just one flea bite. This reaction is a response to the saliva left behind in the bite, as fleas have no venom. The best treatment is prevention. There are effective topical and chewable flea preventatives available from your veterinarian.


Flies may not sting, but some do bite. While their bite has no venom, their saliva can cause an allergic reaction. Biting flies tend to be found in places with livestock (horses, cattle, swine) so your suburban or urban cat is less at risk from these.


Some cats are allergic to mosquito bites, known as mosquito bite hypersensitivity. These cats usually have areas of hair loss and redness on their face. It can be quite uncomfortable for them. There is no cure for mosquito bite hypersensitivity. The best treatment is avoidance — keep windows and doors closed during dusk hours when mosquitoes are most active.


There are several types of scorpions throughout the United States, and they all sting. Some scorpions prefer to use their pinschers rather than injecting their venom, but it varies by type, and some are more venomous than others, which means their sting is more painful.

Most cats heal from scorpion stings without intensive treatment. but they may need a trip to the veterinarian for pain relief.


Two of the deadliest venomous spiders in the United States are the black widow and the brown recluse. The good news is that these spiders prefer to hide rather than bite; they normally only bite in self-defense when their home is threatened. Their venom can cause severe reactions in cats, so if you suspect a spider bite, bring your cat to your veterinarian immediately. The location of the bite can be important as bites to the face may be more severe than those to a paw.

Protecting Your Cat from Insect Bites and Stings

Cats are very sensitive to the chemicals used in insect repellents, so using a pesticide in your home is not recommended. Diatomaceous earth (fossilized plankton) or boric acid may help when applied around the outside of the house. These products won’t deter anything that can fly, but they might be enough to keep crawling insects outside.

Turning on a ceiling fan will help keep some flying bugs off your cat, since mosquitoes’ wings aren’t strong enough to fight the wind from the fan.


Insect Stings, Merck Manual

Biting Flies, Illinois Department of Public Health

How Scorpions Choose Between Their Stinger Or Pincers

Venomous Spiders by State



Flea Control and Flea Bite Allergies in Cats

Is Your Indoor Cat Safe from Parasites?

Pets and Bedbugs: How to Safely Get Rid of the Bedbugs


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