Acyclovir ointment (5%) is a prescription antiviral used to treat first outbreaks of genital herpes and herpes simplex virus sores in people with weakened immune systems. It works by slowing the growth and spread of the herpes virus, giving the body’s immune system a better chance to control the infection. The ointment is a specific formulation, distinct from acyclovir cream, and each version is designed for different situations.
Approved Uses for the Ointment
The FDA approved acyclovir ointment for two specific purposes: managing initial genital herpes outbreaks and treating limited, non-life-threatening herpes simplex sores in immunocompromised patients. That second group includes people with HIV, those on chemotherapy, or anyone taking medications that suppress the immune system. In these patients, herpes sores can be more severe and slower to heal on their own, making topical antiviral treatment especially useful.
It’s worth noting what the ointment is not for. It won’t prevent future herpes outbreaks, and it isn’t the standard treatment for recurrent genital herpes in otherwise healthy people. For recurring episodes, oral antiviral medications are generally more effective because they reach higher concentrations throughout the body.
Ointment vs. Cream: They Treat Different Things
Acyclovir comes in both an ointment and a cream, and the two are not interchangeable. The cream is formulated specifically for cold sores (fever blisters) on the face or lips. It should not be applied to genital herpes sores. The ointment, by contrast, is the version used for genital herpes and for herpes sores in immunocompromised patients.
The application schedules also differ. Acyclovir cream is typically applied five times a day for four days. The ointment requires more frequent use: six times a day, roughly every three hours, for seven days. That more intensive schedule reflects the ointment’s role in treating more significant outbreaks where longer antiviral coverage matters.
How Well It Works
For first-episode genital herpes, topical acyclovir meaningfully shortens the course of the outbreak. In clinical trials, people using the medication had a median pain duration of 4 days compared to 8 days with a placebo. Total healing time dropped from 14 days to 8 days, and the period during which the virus was actively shedding (and most contagious) fell from 11 days to just 4. New lesion formation was also nearly eliminated in the treatment group.
For recurrent episodes, the benefits were still measurable but less dramatic. Symptom duration dropped from a median of 6 days to 3 days, and healing time shortened from 6 days to 4. Only 5% of treated patients developed new lesions during a recurrence, compared to 29% of those using a placebo. Even so, oral antiviral pills remain the preferred approach for recurrent outbreaks in most patients because they deliver the drug more efficiently throughout the body.
How to Apply It
Apply enough ointment to fully cover each sore and a small border of surrounding skin. Use a finger cot or rubber glove during application. This serves two purposes: it prevents you from spreading the virus to other parts of your body (a process called autoinoculation), and it protects the sores from bacteria on your hands.
Stick to the six-times-daily schedule as closely as possible, spacing doses about three hours apart during waking hours. The full seven-day course should be completed even if sores start to look better before then. Starting treatment as early as possible after symptoms appear gives the best results, since the antiviral is most effective while the virus is actively replicating.
Side Effects
Topical acyclovir is well tolerated by most people. The most commonly reported side effects are mild and localized: temporary burning or stinging at the application site, mild pain, itching, or a rash. These reactions are usually brief and don’t require stopping the medication. Because very little of the drug is absorbed through the skin into the bloodstream, systemic side effects (the kind that affect your whole body) are rare with topical use.
Pregnancy and Breastfeeding
Acyclovir ointment is classified as Pregnancy Category B, meaning animal studies have not shown harm to a fetus, but no well-controlled studies exist in pregnant women. The systemic absorption from topical application is minimal, which is somewhat reassuring, but the general guidance is to use it during pregnancy only when clearly needed.
For breastfeeding, the picture is similar. It’s unclear whether topically applied acyclovir reaches breast milk, though the amount absorbed through the skin is very small. Oral acyclovir does appear in breast milk at measurable levels. One important practical point: if you have active herpes sores near or on the breast, you should avoid nursing from that side regardless of medication use, to prevent direct transmission to the infant.
Prescription Status
In the United States, acyclovir ointment requires a prescription. The cream version for cold sores also requires a prescription in the U.S., though in the UK and some other countries, lower-strength acyclovir creams for cold sores can be purchased over the counter at pharmacies. The ointment formulation, used for genital herpes, is prescription-only in all major markets.