Dogs, just like humans, are often prescribed antibiotics to fight infections. But antibiotics only work on bacterial infections, which is why your doctor won’t prescribe them to you for a basic cold or flu (which is caused by a virus).1

In both dogs and humans, antibiotics work by attacking and killing the bacterial infection while preventing it from growing any further.

The types of infections that your vet will likely prescribe antibiotics for include:2

  • Bacterial infections
  • Respiratory infections
  • Gastrointestinal infections
  • Skin or tissue infections

Some of the most common antibiotics prescribed for dogs include: Cephalexin, Clavamox, Clindamycin, Gentamicin, and Doxycycline.3

Dog Antibiotics | Dr. Marty

But unfortunately, dog antibiotics aren’t all good news. They can come with a whole host of side-effects for your pooch. Their benefits still vastly outweigh these side-effects, but you should still work with your vet to determine whether your dog really needs them. If so, it’s important that you discuss the simultaneous use of probiotics for your pup.

The Potential Side Effects of Antibiotics on Dogs

If your dog is currently taking antibiotics for an infection, you should be aware of the following possible side-effects:


It can be hard to tell whether your dog is vomiting because of their sickness or because of the drugs. But some types of dog antibiotics, like Clavamox and Doxycycline, seem to more commonly cause vomiting in dogs.4,5

Be sure to follow your vet’s advice on whether the antibiotic should be taken with or without food. You should check in with them if your dog is vomiting after taking the medication, as this may mean that it’s not being fully absorbed into their system.


Diarrhea in dogs can be very common while taking an antibiotic. After all, the medication isn’t just killing the bad bacteria… it’s killing the good bacteria too. And this imbalance in the gut flora will often result in diarrhea.6It’s a really good idea to work out a pup probiotic plan with your vet to help support the gut during this time. Read on below for some more info on doggy probiotics.

Allergic Reactions

An allergic reaction is a serious side-effect, so if you believe that your pup is having a reaction to an antibiotic, you should stop administering it and call your vet immediately. Common symptoms of an allergic reaction in dogs include swelling, rash, hives, difficulty breathing, fever, vomiting, or seizures.7

A Disinterest in Food

Dog Antibiotics | Dr. MartyWhile your dog is taking antibiotics, they might start to “go off” their food. This is not uncommon. It may happen because of the same gut flora upset that’s causing diarrhea.

Consider feeding your dog a “bland” diet of soft, easily digestible foods. Bland diets are usually made up of one carbohydrate source and one lean protein – ie. boiled rice and a lean chicken breast. Bland diets help to rest the gastric system and assist in normal stool production. A vet will generally recommend that your pet fasts for at least 12 hours prior to allow the intestinal system to relax.8

Yeast Infections

One of the reasons that humans take probiotics with antibiotics is because of the potential to end up with a yeast infection. The same goes for pups. Dog antibiotics kill off the good bacteria in the digestive tract, often causing an overgrowth of the less friendly bacteria that naturally live in the gut. A yeast infection in your furry best friend may appear as a rash, itchiness, eczema, lesions, diarrhea, or food allergies.9

Talk to your vet if you suspect a yeast infection, or better still, ask that they prescribe your dog probiotics when they first prescribe your dog antibiotics.

Antibiotic-Resistant Superbugs

While antibiotics can be life-saving, they’re also over-used in doctors surgeries and vet clinics alike. Even though dog antibiotics are useless against viruses, they are often prescribed as a “just in case” measure. But this overuse of antibiotics is creating antibiotic-resistant mutant superbugs which can’t be defeated with antibiotics. The effect of this is two-fold, both equally serious: On a smaller scale, your dog may develop a resistance to a life-saving drug. On a larger scale, it’s creating a worldwide threat that could be catastrophic for medicine as we know it.10,11

Can You Give Your Dog Human Antibiotics?

Many people ask this because it seems like a logical, cheaper alternative. And, it’s true that humans and pets do share some antibiotics in common. However, it’s more about the dosage than the drug itself, and dosage is not something to ever play with in medicine … both human medicine and veterinary medicine. Also, without your dog being properly diagnosed by an expert, you may be treating them incorrectly for the illness that they have, placing them at even more risk. Always consult a veterinarian for diagnosis and treatment plans.

Can I Give My Dog Probiotics?

Yes! This is perhaps the best thing that you can do for a dog on antibiotics. Probiotics will help to keep your pooch’s gut flora balanced by adding in more friendly bacteria while the antibiotic is killing everything (good and bad) in sight. Scientific studies even show that taking probiotics may help to enhance your dog’s immunity.12

Talk to your vet about which probiotic supplements are right for your dog. You can find them in powders, capsules, chews, and even in dog food.

The Bottom Line

It’s easy to develop a love-hate relationship with antibiotics, but at the end of the day, these drugs are a miracle of science. Indeed, the discovery of penicillin increased life expectancy (for humans) by eight years just between 1944 and 1972.13

So if your beloved pet is required to take them, keep an eye out for any of these side-effects, and try to support their health with a good probiotic.

For more tips on taking good care of your beloved pooch, keep reading on the Dr Marty Pets blog:
Gurgling Stomach in Dogs: What Does It Mean?
Heartworm Disease: Does Your Dog Have It? (and how to help)