Short answer
Antimicrobial is the broad term for agents acting against microbes. Antibiotic, in CDC’s clinical usage, means an antibacterial drug. Thus every antibiotic is an antimicrobial, but an antiviral or antifungal is not an antibiotic in that usage. 1 2
Antibiotics are a subset of antimicrobials; antivirals and antifungals are other antimicrobial categories.
On this page
At a glance
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| Question | Antimicrobial | Antibiotic |
|---|---|---|
| Breadth | Broad umbrella | Bacteria-directed subset |
| Examples | Antibiotic, antiviral, antifungal | Penicillin or ciprofloxacin |
| Treats viral infection? | Some antimicrobial types can | Antibiotics do not |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Antimicrobial. A substance or drug that kills microbes or inhibits their growth, including agents directed at bacteria, fungi or viruses. 1
Antibiotic. An antimicrobial drug directed against bacteria. 2
Key differences
Classify the target organism first. CDC’s resistance glossary groups antibiotics with other antimicrobial agents according to the microbes they act against. Calling every anti-infective drug an antibiotic hides an important treatment boundary. 1 2
How to tell them apart
Look at the diagnosis and product type: a drug targeting bacteria is an antibiotic; a drug targeting viruses is an antiviral antimicrobial. Medical treatment must follow a clinician’s diagnosis and drug-specific guidance. 1 2
Where they overlap
An antibiotic belongs to both categories. Both words can appear in discussions of resistance, because bacteria, fungi and viruses may each have resistance to their respective drugs. 1 2
Edge cases
The adjective antimicrobial can also describe surface agents in other contexts; this article uses CDC’s drug-focused classification. Some drugs have more than one effect, and older or informal uses of antibiotic can be broader. 1 2
Why the distinction exists
The umbrella term makes it possible to discuss resistance across microbial groups while the narrower term identifies antibacterial therapy. 1 2
Common misconceptions
Antibiotics do not work against viruses merely because viruses are microbes. “Antimicrobial resistance” is wider than antibiotic resistance. 1 2
Examples
Penicillin is an antibiotic and an antimicrobial. An antiviral medicine is antimicrobial but is not an antibiotic under CDC’s clinical definition. 1 2
Sources
Sources checked October 3, 2026.
- CDC — Glossary of Terms Related to Antimicrobial Resistance. Antibiotic; Antimicrobial.
- CDC — Antibiotic Use and Antimicrobial Resistance. About antibiotics.