How to Prescribe Antibiotics for Diabetic Foot Ulcers with a Penicillin Allergy

Prescribing empirically for a diabetic foot ulcer gets narrow fast when the patient has a penicillin allergy and an eGFR under 60. This walkthrough shows how to move from wound assessment to a signed prescription without stalling on formulary or safety checks.

Step 1: Confirm the wound and diagnosis are documented

Before any drug shortlist is useful, the encounter needs an active DFU diagnosis, a wound status (infected, colonized, clean), and an updated allergy list. Open the encounter and verify these are present in the smart clinical overview.

Step 2: Rule out beta-lactams as first-line

Cephalexin and amoxicillin-clavulanate are typical first choices for mild DFU infection but are excluded when penicillin allergy is a hard limit. Document the allergy severity so the exclusion is defensible on chart review.

Step 3: Shortlist penicillin-safe options with MSSA and CA-MRSA coverage

• Doxycycline 100 mg PO BID — covers MSSA and CA-MRSA, renally safe, typically tier-one on Part D.
• TMP-SMX DS PO BID — good MRSA coverage; monitor potassium and adjust for eGFR 48.
• Clindamycin 300 mg PO QID — reserve for confirmed susceptibility; watch for C. difficile.

Step 4: Check coverage before you sign

Run the shortlist against the patient's plan. Tier-one generics should lead; prior-auth options are acceptable if you can document the failure or contraindication of first-line drugs.

Step 5: Write the sig and keep the order as draft for provider signature

Prefill medication, strength, route, dose, frequency, duration, and quantity. Leave the status as Draft until the responsible provider reviews and signs.

For the broader workflow, see the diabetic foot care pathway and how to add Orders and Rx to an encounter.