Acyclovir: what it does and when to use it
Acyclovir is a common antiviral used for herpes simplex (cold sores, genital herpes) and varicella-zoster (shingles). It doesn’t cure these viruses, but it can shorten outbreaks, ease symptoms, and reduce viral shedding when you start it early. Most people get it as pills or a topical cream; in severe cases or for people with weak immune systems it’s given by IV in hospital.
How acyclovir is used
For best effect, begin acyclovir as soon as you notice symptoms — within 48–72 hours is ideal. Typical adult oral options include short courses for cold sores and longer courses for first-time or severe genital outbreaks. For shingles, higher-frequency dosing is common for about a week. Topical acyclovir can help mild cold sores but is less powerful than oral treatment for serious or recurrent infections. Your doctor will pick the dose and length based on the type of infection, your age, and kidney function.
Side effects, interactions & practical tips
Common side effects are mild: nausea, headache, or stomach upset. Less common but important problems include dizziness, confusion (mainly in older adults), and kidney issues — especially if you’re dehydrated or already have kidney disease. Drink plenty of water while taking acyclovir and tell your provider if you take other medications that affect the kidneys.
Acyclovir’s clearance can be slowed by certain drugs (for example, probenecid) and the risk of kidney injury rises if combined with other nephrotoxic medicines. Always list your current meds and supplements to your prescriber. If you have significant kidney disease, your dose will likely need to be adjusted.
Pregnancy and breastfeeding: doctors often prescribe acyclovir in pregnancy when needed, but always discuss risks and benefits with your provider. If you’re breastfeeding, ask whether to continue nursing or delay a dose — your clinician will advise based on the situation.
Practical tips: take pills with a glass of water, stick to the schedule so blood levels stay steady, and finish the prescribed course even if symptoms improve. Don’t share your medicine. If a topical cream is used, wash hands after applying and avoid getting it in your eyes.
When to call a doctor: severe or spreading rash, high fever, signs of kidney trouble (low urine, swelling), confusion, or if you’re immunocompromised. If outbreaks keep happening, ask about suppressive therapy — daily acyclovir can reduce recurrences for many people.
Finally, remember there are alternatives like valacyclovir, which is a prodrug with better absorption and often simpler dosing. Your provider can help you pick the right option for your situation.
Acyclovir for Children: Safety, Dosage, and Side Effects
Acyclovir is a common antiviral medication often prescribed for children to treat viral infections like cold sores and chickenpox. As a parent, it's important to know that this medication is generally considered safe for children when administered at the correct dosage. Your child's doctor will determine the appropriate dosage based on their age, weight, and the severity of the infection. Some possible side effects of Acyclovir include mild symptoms like nausea, diarrhea, or headache, but more serious reactions can occur. Always consult with your child's doctor if you have concerns or if your child experiences any unusual symptoms while taking Acyclovir.