The Stoplight Formulary System was designed to preserve certain antimicrobials and/or provide alerts for adverse effects. YELLOW and RED antimicrobials are covered on this page.
For safety of antimicrobials in pregnancy/breastfeeding or for appropriate use and dosing in pediatrics please refer to the IWK Firstline app. This is available for free for iPhone and Android devices
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| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Acyclovir | GREEN |
| Amikacin | YELLOW |
| Amoxicillin | GREEN |
| Amoxicillin/Clavulanate (Injectable) | YELLOW |
| Amoxicillin/Clavulanate (Oral) | YELLOW |
| Amphotericin B deoxycholate | YELLOW |
| Amphotericin B liposomal (Ambisome) | YELLOW |
| Ampicillin | GREEN |
| Atovaquone | YELLOW |
| Atovaquone-Proguanil | YELLOW |
| Azithromycin | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Caspofungin | YELLOW |
| Cefazolin | GREEN |
| Cefepime | RED |
| Cefixime | YELLOW |
| Cefotaxime | YELLOW |
| Cefoxitin | YELLOW |
| Cefprozil | GREEN |
| Ceftazidime | YELLOW |
| Ceftobiprole | RED |
| Ceftolozane-Tazobactam | RED |
| Ceftriaxone | YELLOW |
| Cefuroxime | GREEN |
| Cephalexin | YELLOW |
| Cidofovir | YELLOW |
| Ciprofloxacin | YELLOW |
| Clarithromycin | YELLOW |
| Clindamycin | YELLOW |
| Cloxacillin | GREEN |
| Colistimethate (Colistin) | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Dalbavancin | RED |
| Dapsone | YELLOW |
| Daptomycin | RED |
| Doxycycline | GREEN |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Ertapenem | YELLOW |
| Ethambutol | GREEN |
| Erythromycin | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Fidaxomicin | RED |
| Foscarnet | YELLOW |
| Fosfomycin IV | RED |
| Fosfomycin PO | YELLOW |
| Fluconazole | GREEN |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Ganciclovir | YELLOW |
| Gentamicin | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Imipenem-Cilastatin | YELLOW |
| Isavuconazole | RED |
| Isoniazid | GREEN |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Letermovir | YELLOW |
| Levofloxacin | YELLOW |
| Linezolid | RED |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Meropenem | YELLOW |
| Metronidazole | GREEN |
| Minocycline | GREEN |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Neomycin | YELLOW |
| Nitrofurantoin | GREEN |
| Norfloxacin | YELLOW |
| Nystatin | GREEN |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Oseltamivir | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Pen G | GREEN |
| Pen V | GREEN |
| Pentamidine | YELLOW |
| Piperacillin/Tazobactam | YELLOW |
| Posaconazole | RED |
| Pyrazinamide | GREEN |
| Pyrimethamine | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Rifabutin | GREEN |
| Rifampin | GREEN |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| Drug | Protection Status |
|---|---|
| Sulphamethoxazole/Trimethoprim (SMX/TMP) | YELLOW |
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Tetracycline | GREEN |
| Tigecycline | RED |
| Tobramycin | YELLOW |
| Trimethoprim | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Valacyclovir | GREEN |
| Valganciclovir | YELLOW |
| Vancomycin | YELLOW |
| Voriconazole | YELLOW |
Spectrum of Activity - the listed microorganisms are expected coverage based on intrinsic properties of each antimicrobial. For specific sensitivities in your area, please see your local antibiograms.
| RED | Protected antimicrobial. Requires AMS review within 72 hours. |
| YELLOW | Protected antimicrobial. Defined criteria for use and/or important safety considerations. |
| GREEN | No restrictions. |
| Drug | Protection Status |
|---|---|
| Zanamivir | YELLOW |
Interchanges provide a therapeutically equivalent alternative to non-formulary antimicrobials or address common dosing issues that arise. These interchanges will expedite and simplify clarifications.
The tables listed here are recommended for Nova Scotia Health. All other previous systemic antimicrobial interchanges will be eliminated. The dosing recommendations below are for adults.
For pediatrics, please refer to IWK Firstline app or other resource.
| Antimicrobial Order | Interchange |
|---|---|
| Azithromycin, oral: any dose/duration OR no duration specified | Azithromycin 500 mg PO daily x 3 days Exceptions: patients admitted to ICU, empiric or confirmed Legionella treatment, treatment of chlamydia infection (single 1 g dose), treatment or prophylaxis of non-tuberculosis mycobacterial infection, maintenance therapy for chronic lung disease or lung transplant recipients, treatment of Lyme or Babesiosis |
| Azithromycin, IV: any dose/duration OR no duration specified | Azithromycin 500 mg IV daily x 3 days Exceptions: patients admitted to ICU, empiric or confirmed Legionella treatment, treatment of chlamydia infection (single 1 g dose), treatment or prophylaxis of non-tuberculosis mycobacterial infection, maintenance therapy for chronic lung disease or lung transplant recipients, treatment of Lyme or Babesiosis Note: IV to PO policy may be implemented in patients appropriate for PO administration |
Last reviewed September 2025
Interchanges provide a therapeutically equivalent alternative to non-formulary antimicrobials or address common dosing issues that arise. These interchanges will expedite and simplify clarifications.
The tables listed here are recommended for Nova Scotia Health. All other previous systemic antimicrobial interchanges will be eliminated. The dosing recommendations below are for adults.
For pediatrics, please refer to IWK Spectrum app or other resource.
| Antimicrobial Order | Interchange |
|---|---|
| Cefazolin 1 g IV any frequency | Cefazolin 2 g IV same frequency Exception: Prophylaxis for Group B Streptococcus during labour and delivery – Cefazolin 2 g IV x 1 dose then cefazolin 1 g IV q8h until delivery |
| Cefazolin __g IV q6h | Cefazolin 2g IV q8h |
| Cefazolin 500mg PO q6h | Cephalexin 500mg PO q6h |
| Cefoxitin 1g IV q6-8h | Cefazolin 2g IV q8h and metronidazole 500 mg IV q12h Exceptions: Pelvic inflammatory disease (PID), post partum x 1 dose for 3rd or 4th degree tears, and surgical prophylaxis for gynecologic procedures. |
| Cefoxitin 2g IV q6-8h | Cefazolin 2 g IV q8h and metronidazole 500 mg IV q12h Exceptions: Pelvic inflammatory disease (PID), postpartum x 1 dose for 3rd or 4th degree tears, and surgical prophylaxis for gynecologic procedures. |
| Ciprofloxacin 400 mg tablet | Ciprofloxacin 500 mg tablet |
| Ciprofloxacin 500 mg IV | Ciprofloxacin 400 mg IV |
| Ciprofloxacin extended release (Cipro® XL) PO |
Ciprofloxacin regular release product, same dose PO (daily dose divided and given twice daily) |
| Clarithromycin, oral: for solution, suspension, tablet; any dose | Azithromycin 500 mg PO daily x 3 days Exceptions: treatment or prophylaxis of non-tuberculosis mycobacterial infection, treatment of H. pylori, skin and soft tissue infections where a beta-lactam cannot be used and there are no suitable alternative oral agents |
| Clindamycin _ mg IV q 6h | Clindamycin _ mg IV q8h (total daily dosage no more than 1800 mg) Exception: Gynecology patients being treated for PID, necrotizing fasciitis, and toxic shock syndrome may receive 900 mg IV q8h |
| Cloxacillin IV any dose q4-6h | Cloxacillin 2g IV q4h |
Last reviewed September 2025
Interchanges provide a therapeutically equivalent alternative to non-formulary antimicrobials or address common dosing issues that arise. These interchanges will expedite and simplify clarifications.
The tables listed here are recommended for NSHA. All other previous systemic antimicrobial interchanges will be eliminated. The dosing recommendations below are for adults.
For pediatrics, please refer to IWK Spectrum app or other resource.
| Antimicrobial Order | Interchange |
|---|---|
| Erythromycin IV (all regimens) | Azithromycin 500 mg IV daily x 3 days Exceptions: erythromycin IV used as motility agent and preterm premature rupture of membranes (pPROM) |
Last reviewed September 2025
Interchanges provide a therapeutically equivalent alternative to non-formulary antimicrobials or address common dosing issues that arise. These interchanges will expedite and simplify clarifications.
The tables listed here are recommended for NSHA. All other previous systemic antimicrobial interchanges will be eliminated. The dosing recommendations below are for adults.
For pediatrics, please refer to IWK Spectrum app or other resource.
| Antimicrobial Order | Interchange |
|---|---|
| Meropenem 1 g or 2 g* IV q8h | Meropenem 500 mg IV q6h Exceptions: *dose is not interchanged if treating CNS, cystic fibrosis, or endophthalmitis infections |
| Metronidazole _ mg IV q 6-8h | Metronidazole _ mg IV q12h Exceptions: C. difficile infection, subdural empyema or brain abscess |
| Metronidazole 250 mg PO/IV q12h | Metronidazole 500 mg PO/IV q12h |
| Micafungin | Caspofungin 70 mg IV on day 1, followed by 50 mg IV q24h Exception: micafungin is to be interchanged to caspofungin 150 mg IV q24h for infective endocarditis |
Last reviewed September 2025
Interchanges provide a therapeutically equivalent alternative to non-formulary antimicrobials or address common dosing issues that arise. These interchanges will expedite and simplify clarifications.
The tables listed here are recommended for NSHA. All other previous systemic antimicrobial interchanges will be eliminated. The dosing recommendations below are for adults.
For pediatrics, please refer to IWK Spectrum app or other resource.
| Antimicrobial Order | Interchange |
|---|---|
| Nitrofurantoin regular as follows: 50 mg PO bid 50 mg PO qid |
Nitrofurantoin Macrocrystals (Macrobid®): 100 mg PO daily 100 mg PO bid Exceptions: Tube and crushing administration, patients with gut absorption issues i.e. ileostomy, short gut syndrome |
| Nystatin oral suspension 100,000 units/mL, any dose, any frequency/schedule | Nystatin oral suspension 500,000 units (5mL) same frequency/schedule. If no frequency written will be dispensed as 5 mL QID for 10 days Exception: Palliative Care |
Last reviewed September 2025
Interchanges provide a therapeutically equivalent alternative to non-formulary antimicrobials or address common dosing issues that arise. These interchanges will expedite and simplify clarifications.
The tables listed here are recommended for NSHA. All other previous systemic antimicrobial interchanges will be eliminated. The dosing recommendations below are for adults.
For pediatrics, please refer to IWK Spectrum app or other resource.
| Antimicrobial Order | Interchange |
|---|---|
| Penicillins - Penicillin G 500 000 IU (300 mg) oral - Penicillin G IV - Penicillin G potassium IV - Penicillin V potassium 250 mg (400 000 IU) - Penicillin V potassium 500 mg - Penicillin V 300 mg |
Penicillins - Penicillin V potassium 300 mg oral - Penicillin G sodium IV - Penicillin G sodium IV - Penicillin V potassium 300 mg (500 000 IU) - Penicillin V potassium 600 mg - Penicillin V potassium 300 mg |
Last reviewed September 2025