Cephalexin

What is this medication for?

• Pyoderma (S. pseudintermedius) and other skin infections
• UTI, soft tissue, respiratory, orthopedic infections

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• stomach/intestinal (vomiting, diarrhea) (Most common)
• Salivation, tachypnea, excitability (Reported)
• Emesis, fever (Reported)

Worth a phone call to your veterinarian

• Toxic epidermal necrolysis (Rare)
• Interstitial nephritis, neurotoxicity (high-dose/prolonged) (Rare)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Beta-lactam hypersensitivity (cross-reactivity with penicillin allergy possible, ~1–15% in humans)
• has or has had: Renal dysfunction, geriatric patients

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Probenecid

Storage and handling

Room temperature, protect from light. Suspensions: refrigerate, discard after 14 days.

Good to know

• No veterinary FDA-approved cephalexin product exists in the US, but it's widely used off-label with published efficacy data for canine pyoderma.
• Time-of-day dosing may matter clinically less than pharmacokinetically (differences in peak levels didn't change time above MIC in one study), but be aware of the variability.