Conditions · FAQ
What side effects can valacyclovir cause when used for cold sores?
Short answer
Valacyclovir can cause headache, nausea, or stomach discomfort. Less common but serious problems include kidney injury, confusion, and severe allergic reactions. Tell your physician about kidney disease and all medicines you take. Get urgent help for trouble breathing, a severe rash, confusion, or a major drop in urination.
Common side effects of valacyclovir include headache, nausea, vomiting, and stomach pain. Not everyone has side effects. If symptoms are bothersome or do not go away, contact your prescribing physician or pharmacist. Do not change your dose on your own or take extra tablets to try to speed treatment.
Serious reactions are less common but need prompt attention. Seek emergency care for trouble breathing, swelling of the face or throat, or a severe rash with blistering or peeling. New confusion, hallucinations, seizures, or a major drop in urination also need urgent medical care. These can be signs of a serious reaction or kidney-related problems.
Before treatment, share your full list of prescription drugs, over-the-counter medicines, and supplements. Tell your physician if you have kidney disease, are on dialysis, or have been dehydrated. Older adults may need extra care with dosing. Drink fluids as your clinician advises, especially if you have a condition that limits how much you should drink. Report any past allergy to valacyclovir or acyclovir.
Sources
Written by the Verra clinical team · Medical review pending
General information, not medical advice. If you're in crisis, call or text 988.