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acyclovir

Pronunciation

Generic Name: acyclovir (oral) (a SYE klo veer)
Brand Name: Zovirax

What is acyclovir?

Acyclovir is an antiviral drug. It slows the growth and spread of the herpes virus so that the body can fight off the infection. Acyclovir will not cure herpes, but it can lessen the symptoms of the infection.

Acyclovir is used to treat infections caused by herpes viruses. Illnesses caused by herpes viruses include genital herpes, cold sores, shingles, and chicken pox.

Acyclovir may also be used for purposes other than those listed in this medication guide.

What is the most important information I should know about acyclovir?

Take this medication for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated.

Treatment with acyclovir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

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Herpes infections are contagious and you can infect other people, even while you are being treated with acyclovir. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.

What should I discuss with my healthcare provider before taking acyclovir?

Do not take this medicine if you are allergic to acyclovir or valacyclovir (Valtrex).

Before taking acyclovir, tell your doctor if you are allergic to any drugs, or if you have kidney disease. You may need a dosage adjustment or special tests during treatment.

FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Herpes virus can be passed from an infected mother to her baby during childbirth. If you have genital herpes, it is very important to prevent herpes lesions during your pregnancy so that you do not have a genital lesion when your baby is born.

Acyclovir passes into breast milk and may harm a nursing infant. Do not take this medication without telling your doctor if you are breast-feeding a baby.

How should I take acyclovir?

Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.

Treatment with acyclovir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

Take each dose with a full glass of water. Drink plenty of water while you are taking acyclovir to keep your kidneys working properly.

Acyclovir can be taken with or without food. Taking acyclovir with food may decrease stomach upset.

Shake the oral suspension (liquid) well just before you measure a dose. To be sure you get the correct dose, measure the liquid with a marked measuring spoon or medicine cup, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

Take this medication for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated. Acyclovir will not treat a viral infection such as the common cold or flu.

Lesions caused by herpes viruses should be kept as clean and dry as possible. Wearing loose clothing may help to prevent irritation of the lesions.

Store acyclovir at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include seizure (convulsions), hallucinations, and urinating less than usual or not at all.

What should I avoid while taking acyclovir?

Herpes infections are contagious and you can infect other people, even while you are being treated with acyclovir. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.

Acyclovir will not prevent the spread of genital herpes. Avoid sexual intercourse or use a latex condom to prevent spreading the virus to others.

Acyclovir side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • pain in your lower back;

  • urinating less than usual or not at all;

  • easy bruising or bleeding; or

  • unusual weakness.

Less serious side effects may include:

  • nausea, vomiting, diarrhea, loss of appetite, stomach pain;

  • headache, feeling light-headed; or

  • swelling in your hands or feet.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Acyclovir dosing information

Usual Adult Dose for Herpes Simplex -- Mucocutaneous/Immunocompetent Host:

Initial episode or intermittent therapy: 200 mg orally every 4 hours (5 times a day) for 10 days
Alternatively, the US Centers for Disease Control and Prevention (CDC) recommends 400 mg orally 3 times a day or 200 mg orally 5 times a day for 7 to 10 days.

Recurrent episodes: 200 mg orally every 4 hours (5 times a day) for 5 days
Alternatively, the CDC recommends 400 mg orally 3 times a day for 5 days, 800 mg orally twice a day for 5 days, or 800 mg orally 3 times a day for 2 days.

Orolabial HSV infection treatment: 400 mg orally 5 times a day for 5 days

IV:
Severe initial episode: 5 to 10 mg/kg IBW IV every 8 hours for 5 to 7 days

Therapy should be initiated at the earliest sign or symptom of primary infection (initial episode) or recurrence.

Usual Adult Dose for Herpes Simplex -- Mucocutaneous/Immunocompromised Host:

Treatment:
Oral: 400 mg orally every 8 hours for 7 to 14 days
IV: 5 mg/kg IV every 8 hours for 7 to 14 days
Treatment dosages recommended by the CDC.

Episodic outbreaks: 200 mg orally every 4 hours (5 times a day) for 5 to 10 days
Alternatively, the CDC recommends 400 mg orally 3 times a day for 5 to 10 days or 7 to 14 days

Orolabial HSV infection treatment:
HIV-infected patients: 400 mg 3 times a day for 7 to 14 days; dosage recommended by the CDC

Therapy should be initiated at the earliest sign or symptom of primary infection (initial episode) or recurrence. Intravenous therapy is indicated for the treatment of primary infection in immunocompromised patients or patients with severe infection.

Usual Adult Dose for Herpes Simplex Encephalitis:

10 to 15 mg/kg IBW IV every 8 hours for 10 to 21 days

Usual Adult Dose for Herpes Simplex -- Suppression:

Chronic suppressive therapy:
Immunocompetent patient: 400 mg orally twice a day; alternatively, 200 mg orally 3 to 5 times a day may be used
HIV-infected patient: 200 mg orally 3 times a day or 400 mg orally 2 times a day
HIV-infected patient, genital herpes: 400 to 800 mg orally 2 to 3 times a day

The safety and efficacy of daily acyclovir suppressive therapy have been documented among patients treated orally for up to six years. However, since the frequency and severity of recurrences may change over time, patients should be reevaluated after one year of therapy to assess the need for continued administration.

Daily suppressive therapy reduces but does not eliminate asymptomatic viral shedding, thus the extent to which it may prevent transmission of infection to others is unknown.

Usual Adult Dose for Herpes Zoster:

Acute herpes zoster:
800 mg orally every 4 hours (5 times a day) for 7 to 10 days
Severe, immunocompromised host: 10 mg/kg IBW IV every 8 hours for 7 to 14 days

Therapy should be initiated within 72 hours after onset of rash, although, during clinical trials, acyclovir was most effective when initiated within the first 48 hours.

Usual Adult Dose for Varicella-Zoster:

Chickenpox:
Immunocompetent host: 800 mg orally four times a day for 5 days

Immunocompromised host: 10 mg/kg IBW IV every 8 hours for 7 to 10 days or until no new lesions for 48 hours; after fever abates and if there is no proof of visceral involvement, the patient may be switched to 800 mg orally four times a day

Therapy should be initiated at the earliest sign of chickenpox, no later than 24 hours after onset of rash.

Usual Pediatric Dose for Herpes Simplex:

Neonatal HSV infection:
Less than 3 months: 10 to 20 mg/kg or 500 mg/m2 IV every 8 hours for 10 to 21 days
Some clinicians recommend 10 mg/kg every 12 hours for premature neonates.

Usual Pediatric Dose for Herpes Simplex -- Mucocutaneous/Immunocompetent Host:

3 months to 11 years:
Initial episode: 10 to 20 mg/kg orally 4 times a day or 8 to 16 mg/kg orally 5 times a day for 7 to 10 days
The American Academy of Pediatrics (AAP) recommends 40 to 80 mg/kg orally per day in 3 to 4 divided doses for 5 to 10 days.
Maximum dose: 1 g per day

12 years or older, over 40 kg:
Initial episode, severe initial episode, and recurrent episodes: Adult dose

Usual Pediatric Dose for Herpes Simplex -- Mucocutaneous/Immunocompromised Host:

Treatment of mucocutaneous HSV infection:
Oral: 1 g orally per day in 3 to 5 divided doses for 7 to 14 days; dosage recommended by the AAP

IV:
3 months to 11 years: 5 to 10 mg/kg or 250 to 500 mg/m2 IV every 8 hours for 7 to 14 days
12 years or older, over 40 kg: Adult dose

Usual Pediatric Dose for Herpes Simplex Encephalitis:

3 months to 11 years: 10 to 20 mg/kg or 500 mg/m2 IV every 8 hours for 10 to 21 days
12 years or older: Adult dose

Usual Pediatric Dose for Herpes Simplex -- Suppression:

Oral:
Less than 12 years: 80 mg/kg/day orally in divided doses 3 to 4 times a day, not to exceed 1 g/day
12 years or older: Adult dose

Immunocompromised host: 5 mg/kg IV every 8 or 12 hours or 250 mg/m2 IV every 8 hours during risk period

Oral acyclovir prophylaxis is recommended by the U.S. Public Health Service and Infectious Diseases Society of America for chronic suppressive therapy in HIV-infected individuals, including infants and children, with frequent or severe recurrences. Daily suppressive therapy reduces but does not eliminate asymptomatic viral shedding, thus the extent to which it may prevent transmission of infection to others is unknown.

Usual Pediatric Dose for Herpes Zoster:

Oral:
Immunocompetent host:
12 years or older: 800 mg orally every 4 hours (5 times a day) for 5 to 10 days

HIV-infected host: 20 mg/kg (up to 800 mg per dose) orally 4 times a day for 7 to 10 days; dosage recommended by the CDC

IV:
Immunocompetent host:
Less than 1 year: 10 mg/kg IV every 8 hours for 7 to 10 days
1 year to 11 years: 10 to 20 mg/kg or 500 mg/m2 IV every 8 hours for 7 to 10 days
12 years or older: Adult dose

Immunocompromised host:
Less than 12 years: 10 to 20 mg/kg IV every 8 hours for 7 to 10 days
12 years or older: 10 mg/kg IV every 8 hours for 7 to 10 days

Therapy should be initiated within 72 hours after onset of rash, although, during clinical trials, acyclovir was most effective when initiated within the first 48 hours.

Usual Pediatric Dose for Varicella-Zoster:

Chickenpox:
Immunocompetent host:
2 years or older, 40 kg or less: 20 mg/kg orally 4 times a day for 5 days (maximum: 3200 mg/day)
2 years or older, over 40 kg: Adult dose

Immunocompromised host:
Oral:
HIV-infected host: 20 mg/kg (up to 800 mg per dose) orally 4 times a day for 7 days or until no new lesions for 48 hours

IV:
Less than 1 year: 10 mg/kg every 8 hours for 7 to 10 days or until no new lesions for 48 hours
1 year to 12 years: 10 to 20 mg/kg or 500 mg/m2 IV every 8 hours for 7 to 10 days or until no new lesions for 48 hours
12 years or older: Adult dose

Therapy should be initiated at the earliest sign of chickenpox, no later than 24 hours after onset of rash.

What other drugs will affect acyclovir?

Before taking acyclovir, tell your doctor if you are also taking probenecid (Benemid). If you are using probenecid, you may not be able to use acyclovir, or you may need dosage adjustments or special tests during treatment.

There may be other drugs that can affect acyclovir. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Where can I get more information?

  • Your pharmacist can provide more information about acyclovir.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 5.06. Revision Date: 2010-12-15, 4:58:39 PM.

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