Acyclovir ophthalmic: uses, how to apply it, side effects
Last updated September 6, 2026.
**Acyclovir ophthalmic is a prescription eye ointment in the nucleoside analog antiviral class.** It blocks herpes simplex virus from copying its DNA. Worsening pain or vision needs prompt eye care because this infection affects your cornea.
What does it treat?
You may receive this medicine for herpes simplex keratitis with branching corneal sores called dendritic ulcers. Symptoms can include a painful, watery, red eye and light sensitivity, but an eye examination is needed to identify the cause.
How do you take it?
The adult label dose of 3% ointment is a 1 cm ribbon inside your lower eyelid pocket 5 times daily, about every 3 hours while awake. Once your clinician confirms healing, use the same amount 3 times daily for 7 days. Do not exceed the prescribed schedule; 5 applications daily is the initial labeled regimen. Wash your hands, keep the tip clean, and close your eye for 1 to 2 minutes afterward. Meals do not matter. Apply a missed dose when remembered unless the next is nearly due; never double it. Stop for an allergic reaction and get help; call promptly for worsening eye symptoms.
Side effects to know
- Common: You may experience stinging, eyelid irritation, or inflammation of your eye surface.
- Serious: Stop using it and get immediate help for hives or swelling of your face, lips, or tongue. New or worsening eye pain, light sensitivity, or blurred vision requires same-day eye care.
Who should not take it?
Do not use it if you are allergic to acyclovir or valacyclovir. Avoid contact lenses during treatment. Tell your clinician about a weakened immune system, all medicines, pregnancy, or breastfeeding. Pregnancy registry findings were reassuring but cannot establish safety; breast milk exposure after eye application is unknown. The label identifies no clinically significant interactions with other topical medicines and gives no specific alcohol restriction.
When is it an emergency?
For overdose or swallowed ointment, call Poison Control at 1-800-222-1222 without waiting for symptoms. The label lists no specific overdose symptoms and says overdose from eye application is unlikely. Call 911 for collapse or breathing trouble. Sudden vision loss requires immediate emergency evaluation.
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Common questions
What is the maximum daily dose?
Use a 1 cm ribbon per affected eye 5 times daily initially. After confirmed healing, use it 3 times daily for 7 days. Extra applications are not recommended.
Can I drink alcohol?
The label specifies no alcohol restriction. This does not establish that every combination is safe. Check restrictions for your other medicines.
Can I use it during pregnancy or breastfeeding?
Discuss treatment with your clinician. Systemic acyclovir pregnancy data showed birth defect rates similar to background rates, but had limitations. Milk levels and infant effects after eye use are unknown.
Do I need to use it with food?
No meal timing is required. You can eat normally. Apply it only to your eye as directed.
What happens if I use too much?
The label describes overdose from eye application as unlikely. It provides no characteristic overdose signs. Call Poison Control at 1-800-222-1222 for excess use or swallowing; call 911 for collapse or breathing trouble.
Can I use other eye medicines?
The label reports no clinically significant interactions with other topical drugs. Give your clinician your full medication list. Ask how to space prescribed eye products.