Aciclovir (tablets)

Sounds like 'ay-SYE-kloe-vir'

Key points about aciclovir tablets

  • Aciclovir tablets are used to treat viral infections.
  • Aciclovir is also known as Lovir® or Zovirax®.
  • Find out how to take them safely and possible side effects.
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Aciclovir is used to treat infections caused by viruses, such as herpes simplex virus (which causes cold sores around your mouth and genital herpes) and varicella zoster (which causes chickenpox and shingles). It is also used to prevent viral infections in people with a weakened immune system, eg, if you are receiving cancer medicine (chemotherapy).

Aciclovir works by stopping viruses reproducing. It does not kill the virus. By taking aciclovir, your infection will heal quicker and it will be less severe.

In Aotearoa New Zealand, aciclovir is available as tablets in different strengths (200 mg, 400 mg and 800 mg).

  • The dose of aciclovir will be different for different people, depending on the type of infection and whether it is used to treat or prevent an infection.  
  • Usually, the dose ranges from 200 mg to 800 mg and is taken 2–5 times a day.
  • For most infections, you should start to feel better after taking aciclovir for a few days.
  • Always take your aciclovir exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much aciclovir to take, how often to take it and any special instructions.

  • Swallow your aciclovir tablets with a glass of water. If you have difficulty swallowing the tablet, the tablet can be dissolved in a small glass of water. Stir until dissolved. Drink all the water to make sure you get the full dose.
  • Timing of your doses: Separate your doses out evenly during the day. For example, if your dose is to be taken 5 times a day, take a dose about every 4 hours such as 7am, 11am, 3pm, 7pm and 11pm. You can take aciclovir with or without food.     
  • Missed dose: If you forget to take your dose, take it as soon as you remember but, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
  • Keep taking aciclovir until the course is finished. Do not stop taking it, even if you feel better after a few days. Your doctor will advise you on how long to take aciclovir for (usually 5–10 days).

Here are some things to know when you're taking aciclovir. Other things may be important as well, so ask your healthcare provider what you should know about.

  • Drink plenty of water while taking aciclovir. It's important to drink plenty of water so you don't get dehydrated while taking aciclovir. This could affect your kidneys. This is especially important for older adults. 
  • Protect yourself from too much sunlight while being treated with aciclovir. Always cover up and apply a thick layer of broad spectrum sunscreen (at least SPF 30) when outside. Do not use sunbeds. 

Like all medicines, aciclovir can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Seizures (fits)
  • Symptoms of easy or unusual bruising or bleeding
  • Tell your doctor immediately or ring Healthline 0800 611 116.
  • Confusion
  • Tell your doctor
  • Nausea (feeling sick) or vomiting
  • Try taking aciclovir after a meal.
  • Tell your doctor if nausea continues to bother you.
  • Stomach pain
  • Diarrhoea (runny poos)    
  • Drink lots of fluids.
  • This may settle after a few days.
  • Tell your doctor if it is bothering you.
  • Headache, feeling sleepy, dizzy or tired
  • Be careful when driving or using tools until you know how this medicine affects you.
  • Signs of an allergic reaction such as skin rash, itching, swelling of your lips, face, and mouth or difficulty breathing
  • Tell your doctor immediately or ring Healthline 0800 611 116.
For more information on side effects, see the Medsafe consumer information leaflet Lovir(external link).

Did you know that you can report a side effect of a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product(external link)

The following links have more information on aciclovir. 

Lovir(external link) Medsafe NZ Consumer Medicine Information
Aciclovir (tablet)(external link) NZ Formulary


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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Maya Patel, MPharm PGDipClinPharm, Auckland

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