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My 16lb dog accidentally ate a 500mg cephalexin pill. Is she okay?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed Small (up to 22lb) | Female | spayed | 3 years and 1 month old | 18 lbs

My other dog Is on cephalexin 500mg for a ear/skin allergy/infection. But KC (16lbs) accidently got the cheese wrapped pill and ate it even though I tried to make her spit it out. Is she going to be okay??

3 Answers

Most Helpful Answer

Answered By Daniel Fonza, DVM

Veterinarian

Published on November 29th, 2017

Hi there and thank you for using Pet Coach to address your concern. At the high end of the dose of 60mg/kg for systemic infections, it would be approximately 436mg every 8 hours for that dose for a 16lb dog. A 500mg capsule will not likely cause any life threatening problems. You may see vomiting and diarrhea but this should resolve on its own. If you start to see neurological symptoms such as seizures or a wobbly gait, I would have a veterinarian examine KC. I hope this helps! Please let me know if you have any other questions or concerns and I would be happy to help further.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Jennifer Summerfield, DVM CPDT-KA
Veterinarian, Certified Dog Trainer
Published on September 23rd, 2019
Hi there. Cephalexin is an antibiotic with a very wide margin of safety in dogs, so it's unlikely that this will cause any significant problems. She may have a minor upset stomach today (vomiting or diarrhea), but otherwise should be just fine.

But to be safe, I would recommend calling your regular veterinarian to let them know what happened. They may want you to skip her usual evening dose today, or may have you start some medication to help with stomach issues if she develops any problems.
1Pet Parents found this answer helpful
Answered By Linda G, MS, DVM
Veterinarian
Published on April 7th, 2018
Hello. Cephalexin is a very common antibiotic used in pets & usually does not cause a problem, but your dog may indeed have a sensitivity to it. I am glad you held off giving the medication this evening, but I would try it again tomorrow morning about 30 minutes after she eats. If she holds it down, great but if she vomits then your veterinarian will need to prescribe another antibiotic on Monday if necessary. Continue the steroid as this is the more important medication. Thanks for using Petco Pet Education Center, formerly Petcoach.
1Pet Parents found this answer helpful

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My dog is on Cephalexin. Is this dose safe for renal failure?

It is a high dose (22 mg/kg is average although there is a range because of capsule sizes) and in some cases we would dose reduce this drug with kidney failure (but if your pet has early changes this may not be necessary, is case dependent). I would call your vet to check the dose, he or she may have a reason for this high dose. I hope this helps and thank you for using Petco Pet Education Center, formerly Petcoach!

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Is 1000mg of cephalexin a high dose for a 75-pound dog?

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Thank you for using Petco Pet Education Center, formerly Petcoach! Cephalexin is a commonly used antibiotic and has minimal side effects. Most of the side effects have to do with intestinal signs - mild nausea, diarrhea, or decreased appetite - all of these can be causing Chicharito to be a little bit less active. In rare cases, cephalexin can cause kidney damage, but this is in dogs who already have kidney disease. I hope this helps and am happy to answer any other questions you may have regarding your pets medications!

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Don' t worry about having given her a one off overdose. It is a third generation cephalosporin antibiotic that it's quite often used at high dosages for skin problems. If given continuously at double dosage, I would recommend to check her liver through a blood test but since it just occurred once I would not worry on this occasion.

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How long can my dog safely take cephalexin without causing issues?

Cephalexin is a safe antibiotic and I am not aware of any side effects of long term usage. Using an antibiotic for a long period of time can however result in antibiotic resistance which is a major problem for animals and people. It is difficult to say how long is too long when you're talking about risk for antibiotic resistance. There are general guidelines regarding safe and prudent antibiotic usage - talk to your vet if you have concerns.

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Is twice-daily Cephalexin for dog skin issues safe long-term?

Cephalexin should always be given every 12 hrs due to the half-life of the medication, and sometimes even every 6-8 hrs depending on the severity of the infection. There can be a build up of resistance to frequent use of antibiotics, so I would try to have a more in depth conversation with your vet about long term treatment options that can keep Bruno's skin barrier at optimal levels, such as daily fish oils, prescription diets, and medicated shampoo's. Bruno getting Cephalexin at the frequency that he has been getting it should no affect his liver in a negative way or reduce his lifespan, the main concern here is resistance to the antibiotics over time. Best of luck with your furry friend Bruno moving forward and managing his apparent skin allergies and skin infections. Take care!

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