Two medicines, side by side
Acyclovir vs azithromycin
Acyclovir is labeled for herpes and shingles; azithromycin for bacterial infections. Their labels share no use, so they are not alternatives to each other. Drugs@FDA records approvals of acyclovir since 1982 and of azithromycin since 1991. Pharmacies paid $0.0962 per acyclovir 400 mg tablet and $0.266 per azithromycin 250 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. Azithromycin's other strengths are brand-only: $98.51 per mL (Azasite 1% eye drops). In FDA's classes, acyclovir is a herpes zoster virus nucleoside analog dna polymerase inhibitor and azithromycin a macrolide antimicrobial.
Check it at the source: the acyclovir FDA label on DailyMed (effective July 24, 2026); the azithromycin FDA label on DailyMed (effective December 4, 2025).
Highlights of the acyclovir record
Acyclovir (Zovirax) · label of July 24, 2026
Used for
From the label: indicationsHerpes Zoster Infections: Acyclovir tablets are indicated for the acute treatment of herpes zoster (shingles). Genital Herpes: Acyclovir tablets are indicated for the treatment of initial episodes and the management of recurrent episodes of genital herpes. Chickenpox: Acyclovir tablets are indicated for the treatment of chickenpox (varicella).
On the market
- Earliest approval on file
- March 29, 1982
- Generic labelers
- 66 labelers
- Pharmacy cost
- $0.0962 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 12
Highlights of the azithromycin record
Azithromycin (Zithromax) · label of December 4, 2025
Used for
From the label: indicationsAzithromycin tablets are macrolide antibacterial drug indicated for the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms in the specific conditions listed below. […]
On the market
- Earliest approval on file
- November 1, 1991
- Generic labelers
- 55 labelers
- Pharmacy cost
- $0.266 per tablet
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 11
Source: FDA drug labels via openFDA (Acyclovir label of July 24, 2026, Azithromycin label of December 4, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do acyclovir and azithromycin differ on the record?
In FDA's classes, acyclovir is a herpes zoster virus nucleoside analog dna polymerase inhibitor and azithromycin a macrolide antimicrobial.
Half-life, in each label's words: Acyclovir, “Mean half-life after oral doses of 300 mg/m 2 and 600 mg/m 2 in pediatric patients aged 7 months to 7 years was 2.6 …”; Azithromycin, “Elimination Plasma concentrations of azithromycin following single 500 mg oral and IV doses declined in a polyphasic …”
Generics: acyclovir since 1997; azithromycin since 2005 (Drugs@FDA).
| Acyclovir | Azithromycin | |
|---|---|---|
| Labeled for | Herpes and shingles | Bacterial infections |
| Pharmacologic class | Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpes Zoster Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor | Macrolide Antimicrobial |
| How it works (label) | n/a | Azithromycin is a macrolide antibacterial drug. [see Microbiology ( 12.4 )] |
| Half-life (label) | Mean half-life after oral doses of 300 mg/m 2 and 600 mg/m 2 in pediatric patients aged 7 months to 7 years was 2.6 hours (range 1.59 to 3.74 hours). | Elimination Plasma concentrations of azithromycin following single 500 mg oral and IV doses declined in a polyphasic pattern resulting in a mean apparent plasma clearance of 630 mL/min and terminal elimination half-life … |
| Earliest approval on file (Drugs@FDA) | March 29, 1982 | November 1, 1991 |
| First generic approved | April 22, 1997 | November 14, 2005 |
| Generic labelers (NDC) | 66 labelers | 55 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0962 per tablet (Acyclovir 400 mg tablet) | $0.266 per tablet (Azithromycin 250 mg tablet) |
| 12-month price change | +5% | -26% |
| Boxed warning | No | No |
| Shortage now | No current entry | A presentation being discontinued |
| Recalls recorded | 12 | 11 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 114,717 | 59,712 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to acyclovir
- every medicine labeled for the same conditions