Answer
Usually not concurrently. Switching requires specialist planning and an appropriate medicine-specific washout because serotonin syndrome and other severe reactions can occur.
Sources for this answer
- Nardil 15 mg film-coated tablets Phenelzine 15 mg film-coated tablets — Current selected SmPCemc · Summary of Product Characteristics
- NHS Specialist Pharmacy ServiceNHS Specialist Pharmacy Service · NHS medicine guidance