Acyclovir Dosage For Cold Sores | What Is Acyclovir Ointment Used For?

Acyclovir oral tablet is a drug that’s only available in a generic form. Generic drugs normally cost less than the brand-name version. However, they are not available in all strengths or forms as the brand-name drug in some cases.

Acyclovir is also available in oral capsules, suspension, tablets, cream, and ointment. In addition, acyclovir is available as a drug, only prescribed by a doctor.

This drug can be used as part of combination therapy. Unfortunately, this means you need to take it with other medications.

Table of Contents

What is acyclovir ointment used for?

Acyclovir is used to treat viral infections. These include herpes zoster, genital herpes, cold sores, and varicella.

This drug doesn’t treat herpes infections because the herpes virus stays in your body for a long time and causes symptoms later.

How long does acyclovir take to work?

It may take more than 2 hours to reach the maximum plasma concentration after oral acyclovir treatment. Therefore, symptom reduction can take about three days; However, you should take acyclovir until the prescribed course is completed. Acyclovir works best 48 hours after the onset of symptoms.

Acyclovir dosage for cold sores

A single dose is generally around 200mg to 800mg and may be lower for children.

You can usually take acyclovir 2 to 5 times a day. Try to keep the doses equally throughout the day.

  • 4 times a day – you can take it in the morning, at midday, in the late afternoon, and at bedtime.
  • 5 times a day – you can take it at 7 am, 11am, 3 pm, 7pm, and 11pm.

You can also use the cream for at least 4 days. If the cold sore has not healed after 4 days, you can carry on using the cream for another 6 days.

If your sore still has not healed after a total of 10 days, stop using the cream and consult your doctor.

Acyclovir side effects

Acyclovir oral tablet does not cause drowsiness, but it can cause other side effects.

Common side effects

Some of the common side effects of acyclovir oral tablet include:

Serious side effects

Call your doctor immediately if you have serious side effects. Serious side effects can include:

  • Unusual changes in your behavior and mood. Such as:
    • Aggressive behavior
    • Unsteady movements
    • Confusion
    • Trouble speaking
    • Hallucinations
    • Seizures
    • Coma
    • fatigue
  • Liver problems
  • Contraction in your red blood cells and platelets. 
  • Muscle pain
  • Skin reactions. Such as:
    • Hair loss
    • Rash
    • Breaking or loosening of the skin
    • Hives
    • Stevens-Johnson syndrome. This is a rare allergic skin reaction.
  • Changes in your vision
  • Kidney failure such as:
  • Allergic reactions such as:
    • Trouble breathing
    • Swelling of your throat or tongue
    • Rash
    • Hives

If you’re using acyclovir cream on your skin, this is less likely to get side effects.

Inform your doctor if you take any of the following medicines before taking aciclovir:

  • Cimetidine
  • Mycophenolate mofetil
  • Probenecid
  • Aminophylline or theophylline

How to prevent the side effects of acyclovir?

What to do about:

  • Drink plenty of fluids to avoid dehydration.
  • Sit or lie down to feel better.
  • Do not eat rich or spicy food.
  • Try using an unscented moisturizer if you have a skin allergy.
  • Stay out of the bright sun.


Acyclovir is used for the short-term treatment of genital herpes, cold sores, shingles and chickenpox. It is also used for the long-term treatment of recurrent genital herpes. This drug can cause serious risks if you do not take it as directed.

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