Two medicines, side by side
Acyclovir vs famciclovir
Acyclovir and famciclovir are both labeled for herpes and shingles. Drugs@FDA records approvals of acyclovir since 1982 and of famciclovir since 1994. Pharmacies paid $0.0962 per acyclovir 400 mg tablet and $0.214 per famciclovir 125 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, acyclovir is a herpes zoster virus nucleoside analog dna polymerase inhibitor and famciclovir a herpes simplex virus nucleoside analog dna polymerase inhibitor.
Check it at the source: the acyclovir FDA label on DailyMed (effective July 24, 2026); the famciclovir FDA label on DailyMed (effective September 17, 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 famciclovir record
Famciclovir (Famvir) · label of September 17, 2025
Used for
From the label: indicationsFamciclovir, a prodrug of penciclovir, is a deoxynucleoside analog DNA polymerase inhibitor indicated for: Immunocompetent Adult Patients ( 1.1 ) • Herpes labialis (cold sores) o Treatment of recurrent episodes • Genital herpes o Treatment of recurrent episodes o Suppressive therapy of recurrent episodes • Herpes zoster (shingles) Human Immunodeficiency Virus (HIV) -Infected Adult Patients ( 1.2 ) • Treatment of […]
On the market
- Earliest approval on file
- June 29, 1994
- Generic labelers
- 9 labelers
- Pharmacy cost
- $0.214 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 3
Source: FDA drug labels via openFDA (Acyclovir label of July 24, 2026, Famciclovir label of September 17, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do acyclovir and famciclovir differ on the record?
In FDA's classes, acyclovir is a herpes zoster virus nucleoside analog dna polymerase inhibitor and famciclovir a herpes simplex virus nucleoside analog dna polymerase inhibitor.
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 …”; Famciclovir, “The plasma elimination half-life of penciclovir was 2.0±0.3 hours after intravenous administration of penciclovir to 48 …”
Generics: acyclovir since 1997; famciclovir since 2007 (Drugs@FDA).
| Acyclovir | Famciclovir | |
|---|---|---|
| Labeled for | Herpes and shingles | Herpes and shingles |
| Pharmacologic class | Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpes Zoster Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor | Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor |
| How it works (label) | n/a | Famciclovir is an orally administered prodrug of the anti-alpha herpes viral agent penciclovir [ 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). | The plasma elimination half-life of penciclovir was 2.0±0.3 hours after intravenous administration of penciclovir to 48 healthy male volunteers and 2.3±0.4 hours after oral administration of 500 mg famciclovir to 124 … |
| Earliest approval on file (Drugs@FDA) | March 29, 1982 | June 29, 1994 |
| First generic approved | April 22, 1997 | August 24, 2007 |
| Generic labelers (NDC) | 66 labelers | 9 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0962 per tablet (Acyclovir 400 mg tablet) | $0.214 per tablet (Famciclovir 125 mg tablet) |
| 12-month price change | +5% | -22% |
| Boxed warning | No | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 12 | 3 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 114,717 | 2,753 |
| 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