Aciclovir
Also known as: acyclovir, Zovirax
Aciclovir is an antiviral medicine used for infections such as cold sores, shingles, chickenpox and genital herpes. The NHS says no medicine or treatment removes the herpes virus from the body completely.
- Generic name
- Aciclovir
- Active ingredient
- Aciclovir (variants: acyclovir)
- Product type
- Small-molecule medicine
- Drug class
- Nucleoside antivirals
- Brand names
- UK Zovirax
- Routes
- Oral, Topical, Ophthalmic
- Dosage forms
- Tablet, Solution, Cream, Eye ointment
- Also known as
- acyclovir, Zovirax
- Usual preparations
- The NHS describes tablets, a liquid to swallow, an eye ointment, a cold sore cream and a genital herpes cream; injections are usually given only in hospital. Cold sore cream can be bought at most pharmacies and shops without a prescription. (summary of the cited reference, not a prescription)
- Onset and duration
- The NHS says people should start to feel better after taking or using aciclovir for a few days, and advises starting as soon as the first signs of infection appear.
- Monitoring
- Aciclovir is cleared through the kidneys, so the prescriber may adjust treatment for people with kidney problems.
Availability by country
| Country | Status | Note | Source |
|---|---|---|---|
| UK | Over the counter | Cold sore cream can be bought from most pharmacies and shops | UK |
| UK | Prescription only | Tablets and other forms mostly need a prescription | UK |
Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.
What it is used for
- Cold sores
- Shingles
- Chickenpox
- Genital herpes
- Herpes simplex eye infections
- Preventing these infections in some people with a weakened immune system
How it works in the body
Aciclovir is an antiviral medicine. The NHS says aciclovir stops the herpes virus growing and spreading, which helps the immune system deal with the infection. MedlinePlus describes aciclovir as a synthetic nucleoside analogue antiviral that works by stopping the spread of the herpes virus in the body. The NHS says no medicine or treatment removes the herpes virus from the body completely.
Common side effects
- The NHS lists headache, dizziness or feeling faint, feeling or being sick, diarrhoea, stomach ache, rash, itching, tiredness, a high temperature and a skin reaction after exposure to light as common side effects, which are usually mild.
- The NHS says creams are less likely to cause side effects, though some people get mild burning or stinging that usually goes away quickly.
- For a side effect that bothers someone or does not go away, the NHS suggests speaking to a pharmacist or doctor.
Serious: seek help
- A serious allergic reaction, with signs such as sudden swelling of the lips, mouth, throat or tongue or struggling to breathe, needs a 999 call, according to the NHS.
- Liver problems, kidney problems and changes to blood cells are also listed as serious side effects; the NHS advises calling NHS 111 if someone using or recently using aciclovir thinks they may be having these.
Cautions and interactions
- The NHS advises telling a doctor before use about kidney problems, being over 65, being pregnant or trying to get pregnant, or breastfeeding.
- UK product information lists allergy to aciclovir or valaciclovir as a reason the medicine is not used.
- UK patient leaflets say the doctor may adjust treatment for children, people over 65 and people with kidney problems.
- For people with a weakened immune system, such as HIV or AIDS or a bone marrow transplant, the NHS advises talking to a doctor about the best type of aciclovir.
- UK product information says cimetidine and probenecid can raise aciclovir levels in the blood, and that aciclovir may raise theophylline levels.
- The NHS says there is not enough information to show that herbal remedies or supplements are safe to take with aciclovir, and that they are not tested in the same way as pharmacy and prescription medicines.
- The NHS says alcohol can be drunk while taking aciclovir.
Interactions
Check interactions
Taking Aciclovir with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".
Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.
No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.
Same-class and related medicines
Same class: Nucleoside antivirals
Medicines that share the class of Aciclovir. They are separate medicines with their own licences, doses and interactions, not alternative names for Aciclovir.
Key facts
| Fact | Detail |
|---|---|
| Also called | Acyclovir; brand name Zovirax |
| Type of medicine | Antiviral |
| Used for | Cold sores, shingles, chickenpox, genital herpes and herpes simplex eye infections |
| Forms | Tablets, liquid, cream, cold sore cream and eye ointment |
| Available | Cold sore cream without prescription at most pharmacies and shops |
| Alcohol | The NHS says it can be drunk during treatment |
What is aciclovir used for?
Aciclovir is an antiviral medicine. The NHS says it is used to treat infections such as cold sores, shingles, chickenpox and genital herpes, as well as herpes simplex infections of the eye. It is sometimes used to prevent these infections in people with a weakened immune system. The NHS describes tablets, a liquid to swallow, an eye ointment, a cold sore cream and a genital herpes cream; injections are usually given only in hospital. The NHS says cold sore cream can be bought at most pharmacies and shops without a prescription. Children can usually use the cream or ointment, and may be prescribed tablets for chickenpox and shingles.
How does aciclovir work?
The NHS says aciclovir stops the herpes virus growing and spreading, which helps the immune system deal with the infection. MedlinePlus describes aciclovir as a synthetic nucleoside analogue antiviral that works by stopping the spread of the herpes virus in the body. The NHS says no medicine or treatment removes the herpes virus from the body completely. MedlinePlus says acyclovir does not cure cold sores or genital herpes, does not prevent outbreaks of them and does not stop their spread to other people. The NHS says people should start to feel better after taking or using aciclovir for a few days, and advises starting as soon as the first signs of infection appear. The NHS advises avoiding kissing and oral sex while a person or their partner has a cold sore, until the sores have healed, to reduce the risk of passing on the infection.
What are the side effects of aciclovir?
The NHS lists headache, dizziness or feeling faint, feeling or being sick, diarrhoea, stomach ache, rash, itching, tiredness, a high temperature and a skin reaction after exposure to light as common side effects, which are usually mild. The NHS says creams are less likely to cause side effects, though some people get mild burning or stinging that usually goes away quickly. For a side effect that bothers someone or does not go away, the NHS suggests speaking to a pharmacist or doctor. A serious allergic reaction, with signs such as sudden swelling of the lips, mouth, throat or tongue or struggling to breathe, needs a 999 call, according to the NHS. Liver problems, kidney problems and changes to blood cells are also listed as serious side effects; the NHS advises calling NHS 111 if someone using or recently using aciclovir thinks they may be having these.
Who needs extra care with aciclovir?
The NHS advises telling a doctor before use about kidney problems, being over 65, being pregnant or trying to get pregnant, or breastfeeding. UK product information lists allergy to aciclovir or valaciclovir as a reason the medicine is not used. UK patient leaflets say the doctor may adjust treatment for children, people over 65 and people with kidney problems. For people with a weakened immune system, such as HIV or AIDS or a bone marrow transplant, the NHS advises talking to a doctor about the best type of aciclovir. Aciclovir is cleared through the kidneys, so the prescriber may adjust treatment for people with kidney problems.
Aciclovir with other medicines and alcohol
UK product information says cimetidine and probenecid can raise aciclovir levels in the blood, and that aciclovir may raise theophylline levels. The NHS says there is not enough information to show that herbal remedies or supplements are safe to take with aciclovir, and that they are not tested in the same way as pharmacy and prescription medicines. The NHS says alcohol can be drunk while taking aciclovir.
Frequently asked questions
Does aciclovir cure cold sores or herpes?
The NHS says no medicine or treatment removes the herpes virus from the body completely. MedlinePlus says acyclovir does not cure cold sores or genital herpes, does not prevent outbreaks of them and does not stop their spread to other people. The NHS says aciclovir stops the herpes virus growing and spreading, which helps the immune system deal with the infection.
How soon does aciclovir start to work?
The NHS says people should start to feel better after taking or using aciclovir for a few days, and advises starting as soon as the first signs of infection appear.
Can aciclovir cream be bought without a prescription?
The NHS says aciclovir cold sore cream can be bought at most pharmacies and shops without a prescription. A pharmacist can advise whether it suits the infection in question.
Can people drink alcohol while using aciclovir?
The NHS says alcohol can be drunk while taking aciclovir. A pharmacist or GP can answer questions about an individual situation.
Which medicines can affect aciclovir?
UK product information says cimetidine and probenecid can raise aciclovir levels in the blood, and that aciclovir may raise theophylline levels. The NHS says there is not enough information to show that herbal remedies or supplements are safe to take with aciclovir, and that they are not tested in the same way as pharmacy and prescription medicines.
Connected pages in detail
What each linked page on Anatomy Nexus covers, in a line, for Aciclovir.
Symptoms
- Rash Any change in the colour or texture of the skin.
Drug classes
- Nucleoside antivirals Antiviral medicines used for herpes virus infections such as cold sores, shingles, chickenpox and genital herpes.