Cephalexin for Dogs: Uses, Dosage & Side Effects

See your vet immediately if your dog has facial swelling, hives, trouble breathing, collapse, repeated vomiting, severe diarrhea, or seems much worse after starting cephalexin. Those signs can point to an allergic reaction or another urgent problem.

This article is educational only. Cephalexin is a prescription antibiotic, and the right dose, schedule, and treatment length depend on your dog's weight, infection type, kidney function, and other medications. Never start leftover antibiotics or use a medication prescribed for another pet.

Antibiotics work best when they are matched to the infection. Your vet may recommend skin cytology, a urine test, or a bacterial culture before or during treatment, especially if infections keep coming back or are not improving as expected.

Cephalexin is a first-generation cephalosporin antibiotic used in dogs to treat certain bacterial infections. It works by interfering with the bacterial cell wall, which helps kill susceptible bacteria. In veterinary medicine, it is commonly used for skin and soft tissue infections, especially when Staphylococcus bacteria are involved.

Dogs may receive cephalexin as capsules, tablets, flavored chewable tablets, or a liquid suspension. The veterinary brand Rilexine is FDA approved for dogs, while some other forms are human-labeled products used under your vet's direction. Many dogs tolerate it well, and giving it with food may help reduce stomach upset.

Cephalexin does not treat viral infections, yeast infections, or allergies. If your dog has itchy skin, ear problems, or recurrent sores, the antibiotic may help the bacterial part of the problem, but your vet may also need to look for the underlying trigger.

Cephalexin is most often used for bacterial skin infections in dogs, including superficial pyoderma, infected hot spots, and some wound infections. It may also be prescribed for urinary tract infections, surgical site infections, and bone infections when the bacteria are likely to respond.

Your vet may choose cephalexin when the infection pattern fits common susceptible bacteria, or after testing confirms it is a good match. For recurrent infections, deep pyoderma, draining tracts, or infections that have already failed treatment, a culture and sensitivity test is often the most helpful next step.

Because cephalexin is related to other beta-lactam antibiotics, dogs with a known allergy to penicillins or cephalosporins need extra caution. Tell your vet about any past drug reactions, kidney disease, pregnancy status, or other medications before treatment starts.

Cephalexin dosing in dogs varies by the infection being treated and your vet's plan. A commonly referenced veterinary dose range is 15 to 45 mg/kg by mouth every 6 to 12 hours, with many dogs receiving it every 12 hours for routine skin infections. Osteomyelitis and some more serious infections may use dosing closer to 22 to 30 mg/kg every 8 to 12 hours, but the exact schedule should come from your vet.

Treatment length matters as much as dose. Superficial skin infections may need several weeks of therapy, while deep pyoderma or bone infections can require much longer courses. Stopping early can allow the infection to flare again and may make future treatment harder.

If you miss a dose, give it when you remember unless it is almost time for the next one. Then skip the missed dose and return to the regular schedule. Do not double doses. If your dog vomits after a dose, has severe diarrhea, or refuses the medication, contact your vet before making changes.

The most common side effects of cephalexin in dogs are digestive upset, including vomiting, diarrhea, soft stool, and reduced appetite. Some dogs also seem a little tired, thirsty, or itchy while taking it. Mild stomach upset may improve when the medication is given with food, if your vet says that is appropriate.

Rarely, dogs can have an allergic reaction. Warning signs include hives, a rash, facial swelling, pale gums, trouble breathing, weakness, or collapse. See your vet immediately if any of those signs appear.

Call your vet if your dog develops persistent vomiting, severe diarrhea, marked lethargy, worsening skin lesions, or no improvement after several days. Dogs with kidney disease may need dose adjustments because cephalexin is cleared mainly through the kidneys.

Cephalexin has fewer interactions than some other antibiotics, but it is still important to review your dog's full medication list with your vet. Drugs that affect the kidneys may require closer monitoring when used at the same time, especially in dogs that are older, dehydrated, or already have kidney disease.

Probenecid can reduce cephalexin excretion and raise drug levels. Some veterinarians also use caution when combining cephalexin with certain bacteriostatic antibiotics, because those combinations may not always be ideal for every infection.

Supplements, probiotics, compounded medications, and over-the-counter products still matter. Tell your vet about everything your dog receives, including flea and tick products, pain medications, and any leftover antibiotics from past illnesses.