Aciclovir is a treatment for both types of herpes simplex virus (1 and 2), a condition often transmitted through sexual contact. It is the generic version of the popular brand Zovirax, and functions in the same way.


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PLEASE NOTE: This treatment is not available through our online pharmacy service. This page is for information only. If you are experiencing any of the symptoms related to the condition(s) this medication treats, we strongly recommend that you see your GP in person.

Aciclovir is a medicine produced by Actavis and used to treat both strains of the herpes simplex virus (HSV-1 and -2), available in three different forms; the cream is administered as a thin layer to the blisters or sores the virus causes; the standard tablet is swallowed whole with water; while the dispersible tablet is dropped into a glass of water then swallowed after it has dissolved.

  1. Functions in the affected area right away
  2. Speeds up the recovery process
  3. Available in cream, tablet or dispersible tablet form

The medication is the generic version of the more widely-known herpes treatment, Zovirax. Containing the same active ingredient, Aciclovir performs the exact same function as its branded counterpart.

As well as helping to expedite the healing process when applied to cases of the virus in progress, Aciclovir can also be employed as a preventative measure during the very early stages of reactivation, before blisters or sores have fully surfaced. Doing this helps to limit the intensity of recurrent cases.

Herpes is one of the most common physically communicable viruses. It is characterised by painful blisters and sores in the affected area. Although most people associate the infection with sexual contact, it is possible to transmit HSV-1 (more often oral cold sores) indirectly through the use of shared glassware or utensils. HSV-2 (most typically associated with genital herpes) however, is generally only transmitted through sexual contact.

When in remission, the illness is not contagious. This condition is at its most contagious when blisters and sores have burst, and remains infectious for a period following this. It is best to avoid sexual contact with others until the area has completely healed, in order to limit the chances of infecting someone else.

Currently, there is no cure for herpes, and once contracted, the virus remains present in a person’s system for the rest of their lives. Although the virus does not ever fully go away, symptoms may come and go, with decreasing frequency and severity as a person gets older. Reactivations usually occur when the immune system of the host is in a particularly weakened state, due to illness or fatigue.

Treatment for HSV therefore aims at speeding up the recovery process, and catching reactivations before they can develop. Aciclovir is an effective treatment for herpes, as it gets to work fast, easing symptoms during the active stages of an outbreak, and halting the development of those which are about to happen.

It does this by stopping the virus from reproducing in the body. During an episode, the virus generates a self-sustaining enzyme (DNA polymerase) to help multiply itself, which leads to symptoms. Aciclovir works in the body to prevent the production of this enzyme, thus starving the virus of the growth it needs, and enabling the immune system to push the virus back into remission.

If you require Aciclovir treatment, you should contact your doctor. You cannot purchase this medication from our online clinic.

Active Ingredient

The functioning agent in Aciclovir is a substance of the same name, which belongs to a category of medicines called guanosine analog antivirals. It is one of the most established antiviral drugs in medicine, and was developed in the second half of the 20th century. It is now widely considered an essential medicine.

Aciclovir works by inhibiting the growth of viral cells, which attempt to spread and multiply during an outbreak or reactivation of a herpes infection. When the infection awakens and starts to advance, this process manifests in the form of gential or oral blistering and sores, depending on the strain of the virus.

To help it grow, the herpes virus converts an enzyme called RNA polymerase to DNA polymerase. Aciclovir inhibits this process, and limits the development of the virus. Once the growth of the virus is halted, the immune system is able to tackle the infection. This product will therefore not cure herpes, but it will expedite its progress to dormancy.

Page last reviewed:  20/11/2017


Whichever form of Aciclovir you use, in order to get the most out of the treatment, you should use the product as advised by your doctor. Prior to first use, always read the instructions provided in the patient information leaflet. Doing so will help you to minimise the risk of side potential effects.

  1. If you are using the cream version, gently apply the treatment to the affected area. 
  2. For standard tablets, take one or two, as advised by your doctor, with a glass of water.
  3. Those using the dispersible tablet should dissolve one in a glass of water before consuming.

Then, for all three medications you should:

  1. Repeat this dose at 4-hour intervals, up to a maximum of 5 times a day.
  2. Begin using this treatment as soon as you notice signs of infection.
  3. Keep the affected area as clean and dry as possible.
  4. If you miss a dose, don’t double the amount on your next dose. Continue as normal.
  5. Never use more than the amount advised by your doctor.
  6. If your cold sore has not healed after 9 days of treatment, speak to your doctor.
  7. If your genital herpes persists after 10 days of application, seek medical advice.

For more detailed directions, read the patient information leaflet which comes with your medicine.

Download Aciclovir 200mg tablets patient information leaflet

Download Aciclovir 400mg and 800mg tablets patient information leaflet

Download Aciclovir Cream (Zovirax) patient information leaflet

Page last reviewed:  20/11/2017
Please read the patient information leaflet for this medicine fully before use:

Side effects & Warnings

Side effects

No medicine is suitable for everyone or 100 percent risk-free when it comes to side effects. Aciclovir may induce certain side effects, and although they may only be experienced by a minority of the people who use the treatment, it is important to maintain an awareness of them so that you can take action if you notice them.

1. Aciclovir Cream

Uncommon (1 in 100 people or less):
Burning sensation at application site; irritation, itching or flaking of the skin.

Rare (1 in 1000 people or less):
Redness, hypersensitivity, dermatitis.

2. Aciclovir standard tablets

Common (1 in 10 people or less):
Dizziness, headache, nausea, diarrhoea, stomach pain, vomiting, skin rashes, itching, tiredness, sensitivity to sunlight, fever.

Uncommon (1 in 100 people or less):
Severe rash, hair loss.

Rare (1 in 1000 people or less):
Drowsiness, breathlessness, confusion, hallucinations, sleepiness, agitation, involuntary shaking, loss of coordination, abnormal test results.

3. Aciclovir dispersible tablets

Common (1 in 10 people or less):
Dizziness, fever, headache, nausea, vomiting, diarrhoea, stomach pain, skin rashes, itching, tiredness, sensitivity to sunlight.

Uncommon (1 in 100 people or less):
Skin irritation, hair loss.

Rare (1 in 1000 people or less):
Difficulty breathing, abnormal test results, oral or facial swelling, verbal problems, liver or kidney problems, sensitivity to light, agitation, confusion, feelings of weakness, hallucinations, shaking or tremors, reduced coordination.

The information presented here is not a comprehensive account of known possible side effects. For a more detailed list, refer to the patient information leaflet provided or ask your pharmacist. Consult your doctor if you notice these or any other side effects.


Taking it with other medicines

You should tell your doctor if you are taking or have recently taken any medication for other conditions during consultation for Aciclovir.

At present, Aciclovir Cream is not known to interact with or affect the performance of other medicines.

Probenecid, cimetidine and mycophenolate mofetil may affect your ability to safely use Aciclovir Dispersible tablets.

The use of cimetidine, probenecid, mycophenolate mofetil, ciclosporin, theophylline, or zidovudine may affect your suitability to Aciclovir standard tablets.

Do not take Aciclovir Actavis with any other medications for herpes, unless instructed to do so by a doctor.

Conditions to look out for

Disclose your medical history to your prescriber prior to using this medicine. If you have or have had any of the following conditions, a doctor may choose not to prescribe this treatment: an allergy to any containing ingredients; AIDS; a bone marrow transplant; liver or kidney problems; or any condition which limits the function of your immune system.

Pregnancy and breastfeeding

If you are pregnant, breastfeeding or trying to conceive you should speak to your doctor before you use any of the Aciclovir medications.

Driving and machinery

This medication could make you feel sleepy, drowsy or slow to react. You should check that you have not been effected before you carry out any driving on use of machines.

Lactose intolerance

Aciclovir contains lactose, therefore anyone with an intolerance of sugars should speak with their doctor before using this product.

Page last reviewed:  20/11/2017
Please read the patient information leaflet for this medicine fully before use:


Can I still drink alcohol?

Yes. Aciclovir is not known to be any more likely to cause side effects when consumed with alcohol. However, we would recommend that you only ever drink in sensible amounts, so that you can continue to apply your treatment carefully as and when required.

Will I still be able to drive?

This medicine should not directly affect your motor skills or judgement, meaning that you should be able to drive when using it. However, if this medication causes side effects which you believe may make it difficult for you to drive safely, you should avoid doing so and speak to your doctor.

Can I take the medicine while pregnant?

Aciclovir may cause harm to you or your baby if used during pregnancy or breast-feeding. You should only apply this treatment during pregnancy if your doctor deems it absolutely necessary.

How should I store it?

Below 30°C and in a dry environment. Ensure you keep the packaging sealed when not in use, and away from sources of light and moisture.

Am I allergic to anything in the medicine?

Aciclovir Cream contains aciclovir, cetostearyl alcohol, mineral oil, poloxamer 407, propylene glycol, sodium lauryl sulfate, water, and white petrolatum. If you suspect that you may be allergic to any of these, do not use this product.

The dispersible tablet version contains microcrystalline cellulose, aluminium magnesium silicate, sodium starch glycolate, povidone K30, magnesium stearate, hypromellose, macrogol 400, titanium dioxide [E171], macrogol 8000 and aciclovir. If you are allergic to any of these substances, do not use this medicine.

The standard tablet version contains aciclovir, lactose, magnesium stearate, polyvidone, sodium starch glycollate, E132, E460, colloidal anhydrous silica, and E172. Do not use this treatment if you are allergic or unable to tolerate any of the above.

Is it available over-the-counter?

No. You can only buy this product with a prescription from a doctor. 

Is it right for me?

If you require help managing your herpes virus symptoms, you should arrange to see your GP. They can offer advice and decide the best course of action.


Page last reviewed:  20/11/2017
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