Acyclovir: what it treats and how to use it

Ever had cold sores or shingles and wondered what drugs actually help? Acyclovir is a common antiviral used against herpes viruses — think cold sores (HSV-1), genital herpes (HSV-2) and shingles (varicella-zoster). It slows virus replication so symptoms heal faster and outbreaks can be shorter or less severe.

How people take acyclovir

Doctors prescribe acyclovir in pills, topical cream, or IV for serious infections. Typical oral doses for adults: for a first genital herpes episode you might see 200 mg five times a day or 400 mg three times a day for 7–10 days; for recurrent episodes shorter courses like 5 days are common. For shingles, adult dosing often is 800 mg five times daily for 7–10 days. Long-term suppressive therapy (to reduce outbreak frequency) is usually a lower daily dose—your doctor will choose the best plan for you.

If you have kidney problems, doses and schedules change. That’s because the kidneys clear acyclovir and buildup can cause problems. Always tell your prescriber about kidney disease, other medicines, and pregnancy or breastfeeding so they can adjust treatment safely.

Side effects, precautions, and practical tips

Most people tolerate acyclovir well. Common side effects include nausea, headache, and tiredness. Rare but serious issues include kidney injury (especially if you’re dehydrated or on other kidney-harming drugs) and confusion or tremors in people with severe kidney impairment. Drink enough water while taking the drug and avoid mixing it with other nephrotoxic medicines unless your doctor says it’s okay.

Missed a dose? Take it as soon as you remember unless the next dose is near; don’t double up. Store tablets at room temperature and keep creams away from heat. If symptoms worsen or you get high fever, severe sore throat, or changes in urination or thinking, contact your provider right away.

Pregnant or breastfeeding? Talk to your doctor. Acyclovir is often used in pregnancy for severe outbreaks under medical advice, but your provider should weigh risks and benefits.

Want to buy acyclovir online? Always use a licensed pharmacy and expect to send a valid prescription. Red flags: sites that sell prescription meds without an Rx, no contact info, no licensed pharmacist available, or unusually low prices with sketchy shipping. Look for a clear Canadian address and phone number if you want a Canada-based supplier, and ask whether a pharmacist is available to answer questions. Check pill markings and expiry when your order arrives and report problems to the pharmacy and your prescriber.

If you’re unsure whether acyclovir is right for you, a quick call with your doctor or pharmacist clears things up. They’ll confirm the correct dose, check for interactions, and help you pick a safe pharmacy if you plan to order online.