Medications · FAQ
What side effects can valacyclovir cause?
Short answer
Valacyclovir can cause headache, nausea, stomach pain, or vomiting. Serious problems are less common but can include kidney injury, confusion, and severe allergic or skin reactions. Seek urgent help for trouble breathing, a blistering rash, severe confusion, or very little urine. Ask your prescriber about symptoms that persist.
Common side effects of valacyclovir include headache, nausea, stomach pain, vomiting, and diarrhea. Not everyone has side effects. Let your prescriber know if symptoms bother you, do not go away, or make it hard to take your medicine. Do not change the dose on your own to manage them.
Valacyclovir can sometimes cause serious kidney or nervous system problems. Warning signs include much less urine than usual, confusion, hallucinations, unusual sleepiness, or seizures. Risk can be higher in people with kidney disease, older adults, or people taking more medicine than their kidneys can clear. Dehydration can also raise concern.
Get emergency help for trouble breathing, swelling of the face or throat, a severe blistering or peeling rash, or a seizure. Seek urgent care for new confusion or very little urine. Rare serious blood problems have also been reported, especially in people with severe immune system problems. Share your kidney history and full medicine list with your prescriber before starting treatment.
Sources
Written by the Verra clinical team · Medical review pending
General information, not medical advice. If you're in crisis, call or text 988.