How To Get The Best Dosage Of Aciclovir

Which dosages are used for which conditions

Woman checking the dosages of Aciclovir

Key takeaways

  • Aciclovir dosage changes depending on what and who it's being used to treat

  • 200mg or 400mg dosages are normally used for treating genital herpes and 400mg is used for cold sores

  • A doctor can check the right dosage for you. It be different for different people

  • You may need to switch your Aciclovir dosage depending on your situation

  • There are things you can do to get the most out of your Aciclovir dosage

Contents of this article

Whether you're looking for your first dosage of Aciclovir, you're not happy with your current dosage, or you've had it before and think you might need a different one, you can check how to find the right one for you.

There are different dosages of Aciclovir available, depending on what condition you're using it for and what your personal circumstances are. Make sure you're confident in the dosage you need when you get treatment.

What dosages of Aciclovir are available?

Treatment with Aciclovir can be quite flexible because:

  • There are lots of different dosages and these might need to change as part of your treatment, with dosages ranging from 100 mg to 800 mg or from 5 mg/kg to 10 mg/kg
  • There are lots of different types of formulas: eye ointments, creams, tablets and intravenously
  • How often you need to use Aciclovir per day or how many days for might vary

What exactly your treatment specifics are will be decided by your physician when you’re assessed.

Some of the specific dosages for adults are below:

Local treatment – when you’re using a 'local' treatment of herpes infection it refers to either eye ointment or a skin cream. Usually, you’d use about 1 cm of the ointment for at least 3 days and as much cream as directed by your physician for 5-10 days. 

Suppression of herpes – the commonly prescribed dosage is 400 mg, twice a day, though this might need to be increased if there are recurrences. You might also be told to stop using it every 6–12 months so that your physician can reassess how often recurrence might occur

Genital herpes:

  • If this is occurring for the first time, either 200 mg taken 5 times a day or 400 mg taken 3 times a day will be used for 5 days. If the person is HIV-positive or immunocompromised, then the dosage will be 400 mg five times a day for 7-10 days. Both regimens might be extended if it seems necessary for complete healing
  • If your herpes infection becomes severe then your physician might suggest intravenous infusion
  • For recurrent infections, there are more varying treatments i.e. you can be prescribed either 800 mg, 200 mg or 400 mg. In people who are HIV-positive or immunocompromised, this is 400 mg three times a day


  • When you’re taking tablets, usually 800 mg is prescribed to be taken 5 times a day for 7 days, even in those who are immunocompromised, or 10 mg/kg is recommended for intravenous use for 5 days
  • If you need to have intravenous infusion for 5 days, 5 mg/kg is given unless you’re immunocompromised; in that case, it’s 10 mg/kg

What dosages are used for genital herpes and cold sores?

The dosage you’re prescribed will depend on what condition you need treatment for.

For genital herpes – For the treatment of a first episode of genital herpes, you’d be prescribed 200 mg 5 times a day, alternatively 400 mg 3 times a day both courses usually for 5 days. If the person is HIV-positive or immunocompromised, then dosage changes to 400 mg 5 times a day for 7–10 days. Both regimens might be extended if it seems necessary for complete healing.

For cold sores – for the treatment of a first episode of cold sores (oral herpes), you’ll be instructed to take one 400 mg tablet three times a day. You should take the first tablet as soon as you notice the first symptoms and your course should last five days.

How do I find out the right dosage for me?

The right dosage depends on your personal situation – a doctor can let you know what the right dosage is for you, as this can be different depending on you as a person. The aim of the dosage is for it have maximum efficacy but with less risk of side effects. How they decide will be based on some details like those below:

Weight – if you’re overweight, then you need to be dosed at the recommended dosages using Ideal Body Weight (IBW). 

Age – if you’re elderly, then you’re more likely to have reduced liver function than when you’re younger, so you’ll need a lower dosage. There’s no concrete evidence that Aciclovir is safe and effective in people younger than 2 years, so this isn’t recommended for them.

Health conditions and treatments – if you’re receiving treatment related to your liver, then you might need a specific treatment schedule. For example, for people receiving hemodialysis, the amount of time between dosages has to be changed so there’s an additional dosage after each dialysis session. On the other hand, for people receiving peritoneal dialysis, no additional dosage is needed after the time between dosage has been changed.

You should tell your physician if you’re taking any drugs, since these could interact with Aciclovir. Some of the drugs include those used for:

  • HIV/AIDS – zidovudine 
  • Bacterial or fungal infections – amphotericin B, foscarnet, gentamicin, kanamycin 
  • Cancer – talimogene laherparepvec, cisplatin 
  • Pain relief – Motrin, ibuprofen

When would you switch dosages?

It depends on your situation – it’s possible that you may need to switch your Aciclovir dosage. Your physician is likely to make this decision based on factors like those below:

  • Your response to the current dosage – if your symptoms are not properly controlled by your current dosage you could get assessed by a doctor in order to change to a stronger dosage
  • Starting new course of other medications – if you start to suffer from any other illnesses and need to start taking new medications for that, then you need to let your physician know. This could impact how much of each drug you can take; it can be a balancing act and monitoring of your side effects might be necessary
  • What side effects you experience – for example, normally you’re prescribed a relatively high dosage of Aciclovir for shingles, and this might mean that you have more severe side effects. These should be watched quite carefully, and if the side effects are too detrimental, then changes in the dosage might be recommended

How do you get the most effective Aciclovir treatment?

There are a few things you can do to support your treatment – to get the best experience with your treatment, you should do your best with the following:

  • Learning how to take your medication properly – you should know how that your dosage needs to be taken on time and how to use it e.g. how you need to apply your cream or eye ointment
  • Timing your doses – it’s best to take Aciclovir as soon as possible after the first sign of your symptom e.g., when you first see a chickenpox rash
  • Food and drink – you can use your tablets, capsules and oral suspension with your meals or on an empty stomach, but one thing that could interfere is dehydration. If you’re taking any of these Aciclovir formulas, then you should drink plenty of water. This is particularly important if you’re elderly or taking doses of 400 mg a day or higher
  • Accuracy for measuring doses – if you need to measure out your dosages, you need to try and be accurate, for example if you’re using an acyclovir oral suspension. Using a specially marked measuring spoon or anything else similar and help you measure your dosages.
  • Completing your course – to help clear up your infection, you should always finish your full treatment, even if you’re not feeling your symptoms anymore. in a similar way, don’t take the medication for longer than you’ve been told to
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