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Aciclovir tablets

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 3 minutes read

Aciclovir is a prescription-only antiviral medicine used to treat cold sores, shingles, chickenpox, and genital herpes. It does not cure a viral infection but helps to reduce the severity and length of the outbreak. In people with frequent outbreaks and in those who have a weak immune system, aciclovir tablets can be used to help reduce the number of future outbreaks as a preventative medication.

Aciclovir tablets can be used in both children and adults who have cold sores, genital herpes, chickenpox, and shingles. There are different thresholds for taking these tablets depending on the patient, their medical history, and the type and severity of viral infection.

Doctor’s advice

Conditions it is used for

Shingles, caused by a type of herpes virus (Herpes Zoster) is a viral infection that causes a painful rash with shooting pain on one side of the body only. Usually, the rash appears as blotches on your chest and stomach but can appear in any area of the body including your face, eyes and genitals.

Genital herpes is caused by the same virus as cold sores (Herpes simplex virus or HSV) though a different strand (HSV-2). Speak to your doctor or visit your sexual health clinic as soon as possible if you notice painful blisters which burst to leave red open sores around your genitals (they can also exist on your anus, thighs or bottom). Urinating can also be painful.

Chickenpox is a virus caused by the varicella-zoster virus. It is common among children, but anyone can catch it at any age, but you can only catch it once. When adults get it, the symptoms are usually worse. Chickenpox spots begin as red spots all over the body. These red spots fill with fluid and are called blisters or vesicles. The blisters can burst and then eventually start to scab over. Chickenpox is often a very itchy disease that makes people quite uncomfortable. People may also feel quite poorly with fevers, poor appetite and generalised aches and pains. Chickenpox usually lasts a few weeks. People are infectious from a couple of days before the spots appear until after the spots have all crusted over (usually about five days later).

Aciclovir is not commonly used for cold sores, but there are some circumstances where your doctor will consider prescribing it. If they have, you should take your prescribed dose as soon as you recognise the tingling or burning sensation at the site of the outbreak. Cold sores are an infection caused by the herpes simplex virus – once you’ve had contact with the virus, it lies dormant in the nerves supplying the skin and may flare up from time to time. You might recognise triggers – stress and exposure to the cold or sun are common ones. Unfortunately, aciclovir only treats the symptoms of a cold sore, nothing can cure you of the virus or prevent any future cold sores.

How does it work?

Aciclovir is an antiviral agent that interferes with the growth and replication of viral particles, helping your immune system to target and tackle the virus. 

Aciclovir is best to be used in the initial stages of an outbreak, usually within the first 5 days. For treatment of outbreaks, you will be taking a high dose for a short course, usually for 3-5 days. If you have a weakened immune system, treatment doses are usually double the standard doses for healthy individuals. Suppressive antiviral treatment is an option for frequent (usually around 6 or more per year) outbreaks that are causing distress or if outbreaks are affecting your social life.

Should anyone avoid taking it?

Do not take aciclovir tablets if you have previously experienced an allergic reaction to aciclovir or any ingredients (excipients) used to make aciclovir tablets.

Are there any side-effects?

Aciclovir is generally well-tolerated in most individuals. A small number of patients may experience symptoms of fatigue, headache, feeling dizzy, nausea, vomiting, abdominal pain, itching and a rash (including sensitivity to light). If these happen to you, stop taking the medication and seek advice from your doctor.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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