Acyclovir is used to treat infections caused by certain types of viruses. It treats cold sores around the mouth (caused by herpes simplex), shingles (caused by herpes zoster), chickenpox, and it is also used to treat outbreaks of genital herpes.
Acyclovir is an antiviral drug. However, it is not a cure for these infections. The viruses that cause these infections continue to live in the body even between outbreaks. Acyclovir decreases the severity and length of these outbreaks. It helps the sores heal faster, keeps new sores from forming, and decreases pain/itching. This medication may also help reduce how long pain remains after the sores heal. In addition, in people with a weakened immune system, acyclovir can decrease the risk of the virus spreading to other parts of the body and causing serious infections.
Take this medication by mouth with or without food as directed by your doctor. Drink plenty of fluids while taking this medication unless your doctor directs you otherwise.
If you are using the liquid form of this medication, shake the bottle well before each dose. Carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.
This medication works best when started at the first sign of an outbreak, as directed by your doctor. It may not work as well if you delay treatment.
This medication works best when the amount of drug in your body is kept at a constant level. Therefore, take this drug at evenly spaced intervals. To help you remember, take it at the same times each day.
Continue to take this medication until the full prescribed amount is finished. Do not change your dose, skip any doses, or stop this medication early without your doctors approval.
Tell your doctor if your condition persists or worsens.
Nausea, diarrhea, headache, or vomiting may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Tell your doctor right away if any of these unlikely but serious side effects occur: dizziness, drowsiness, signs of kidney problems (such as a change in the amount of urine, unusual back/side pain), mental/mood changes (such as agitation, confusion, hallucinations), shaky/unsteady movement, trouble speaking.
This medication may rarely cause a life-threatening disorder that affects the blood cells, kidneys, and other parts of the body. This disorder is more likely to occur if you have conditions related to a weakened immune system (such as HIV disease, bone marrow transplant, kidney transplant). Seek immediate medical attention if any of these rare but serious side effects occur: extreme tiredness, slow/fast/irregular heartbeat, easy bruising/bleeding, new fever, bloody/dark urine, severe stomach/abdominal pain, yellowing eyes/skin, sudden vision changes, loss of consciousness, seizures.
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
Store acyclovir capsules, tablets, and suspension at 59°F to 77°F (15°C to 25°C).
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctors approval.
Some products that may interact with this drug include: other drugs that may cause kidney problems (including nonsteroidal anti-inflammatory drugs-NSAIDs such as ibuprofen, naproxen).
Acyclovir is very similar to valacyclovir. Do not use medications containing valacyclovir while using acyclovir.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: change in the amount of urine, extreme tiredness, agitation, loss of consciousness, seizures.