Valacyclovir

Infections

Also known as Valtrex

Valacyclovir is an antiviral that treats cold sores, genital herpes, and shingles. Timing is everything: it works best when you start it at the very first sign — that tingle, itch, or burn before anything shows up on the skin. One honest thing to know: it shortens outbreaks and can prevent them, but it doesn't cure the virus, which stays quietly in your body between flare-ups.

How to take it

When

Start at the very first tingle or burn for best results. Space doses evenly, exactly as prescribed.

Food

Works with or without food. Drink plenty of water while taking it — it protects your kidneys.

Avoid

Don't wait to see if a sore develops — starting late makes the medicine much less effective.

Good to know

It manages outbreaks; it doesn't cure the virus. Tell your doctor if you have kidney problems.

Missed a dose?

Take it as soon as you remember. If it's nearly time for your next dose, skip the missed one and continue on schedule. Never take two doses at once.

Common side effects

Headache
Nausea
Stomach pain
Dizziness

Call a doctor if

Confusion, hallucinations, shakiness, or trouble speaking — especially in older adults or people with kidney problems. Get help now.
Trouble breathing, swelling of the face or throat, or hives — serious allergic reaction. Get emergency help now.
Much less urine than usual, or swelling in your legs — possible kidney trouble. Call your doctor right away.
Unusual bruising, tiny red spots on the skin, fever, or extreme fatigue — call your doctor now.

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.