Aciclovir Tablets (400mg)

  • Used to treat and prevent recurring outbreaks of Herpes
  • Works by stopping the herpes virus from spreading
  • Helps clear the signs and symptoms of herpes and cold sores

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From As low as £18.99

Disclaimer: The prices displayed should only be used as a reference of our prices for this medicine. If you are approved for treatment, our prescribers will decide on a suitable treatment for you to jointly consider.

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What is Aciclovir?

Aciclovir is an antivirus medication used in the treatment of a variety of conditions. It is a common cold sore treatment and is also used in the treatment of genital herpes and other viruses.

Depending on how you prefer to administer your medicine and what your ailment is, Aciclovir can be bought in a cream or tablet form. You can buy Aciclovir tablets from Medicine Direct when you have a prescription from one of our certified doctors.

The cream version of this medication is available to be bought at most supermarkets and registered pharmacies without a prescription.

It is sometimes administered by an injection, but this is only done when you are in a hospital.

If you order before 2pm, we can offer you next day delivery on your tablets.

What is Aciclovir used to treat?

It is commonly prescribed to treat and prevent a recurring attack of herpes, e.g. cold sores and genital herpes. It can also be used to protect those who suffer from low immune systems from contracting the herpes virus. Although it is not possible for a medication to cure the herpes virus, Aciclovir works to slow the growth and spreading of the virus around your body. As a result of this, it will lesson your symptoms of the infection.

Doctors may also prescribe Aciclovir to treat shingles and chicken pox as they are also caused by the herpes virus, varicella zoster.

These tablets work by stopping the herpes virus from spreading, controlling the infection and allowing your body to fight back against the likes of cold sores and genital herpes.

No medicine can remove this virus from your system, but antiviral medication like Aciclovir can help to treat individual cases of the likes of cold sores and genital herpes.

Aciclovir or Valaciclovir, what is the difference?

Valaciclovir is a treatment that is commonly used to treat Herpes Simplex Virus, and Genital Herpes. Valtrex is the branded version of Valaciclovir and is also available from medicine Direct. It is very similar to Aciclovir, however there are some differences between the two which are summarised below.

  Valaciclovir Aciclovir
Drug Type Antiviral Antiviral

Herpes simplex

Genital herpes

Cold sores


Herpes simplex

Genital herpes

Cold sores


Frequency 1 Tablet to be taken twice daily 1 Tablet to be taken 5 times daily
Available Doses 500mg 400mg
Active Ingredients Valaciclovir Aciclovir
Available forms Oral Tablet

Oral capsule

Oral Tablet

Oral suspension

Aciclovir Cream

Prices Prices start from £44.99 Prices start from £18.99


Who can take Aciclovir?

Aciclovir is a relatively safe drug to take and can be used by both adults and children. However, it is not suitable for everyone. You should speak to your doctor about whether this medicine is right for you if you have any of the following:

  • You are allergic to Aciclovir or any of its ingredients
  • You suffer from kidney issues
  • You suffer from a nervous disorder
  • You have liver problems, liver disease or abnormal levels of salts in your blood
  • You suffer from breathing difficulties
  • You are over 65 years of age
  • Are pregnant, trying to conceive or are currently breastfeeding
  • You have a weakened immune system

If you have a weakened immune system from conditions like HIV, AIDS or a bone marrow transplant, you should speak to your doctor about which type of Aciclovir treatment is the most suitable for you.

Possible side effects

As is the case with all medicines, Aciclovir comes with the risk of certain side effects, although not everyone will suffer from them.

Most people will not suffer from any side effects, while others may suffer only minor ones that do not last for long.

Here are some of the most common side effects associated with taking Aciclovir tablets. If you experience any of these, you should keep taking the medication but contact your doctor if these symptoms worry you or do not go away:

  • Feeling dizzy
  • Headaches
  • Diarrhoea
  • Skin being sensitive to sunlight
  • Feeling sick or being sick
  • Stomach pain
  • Feeling tired
  • Itching (skin reaction)
  • High temperature and feeling faint, particularly when you stand up
  • Rash

Please note that this list is not exhaustive. For a list of rarer, more serious adverse reactions, please refer to the Side Effects tab on this product's page.

Aciclovir Dosage

Our pharmacists and prescribers follow NICE guidelines when prescribing Acciclovir.

How much Aciclovir you will need to take will depend on what the tablets are being used to treat.

A single dose generally ranges from between 200g and 800g, although the dose might be lower for children. Your doctor will instruct you how much to take and you should follow their instructions precisely.

Always read your prescription and the patient information leaflet, which will come with your medicine, before you start to take it.

How to take Aciclovir

Your doctor will usually instruct you to take Aciclovir between 2 and 5 times a day. You should space these doses out evenly throughout the day.

If you take the tablets 4 times a day, try to take it in the morning, at midday, in the late afternoon and finally in the evening.

If you are instructed to take it 5 times a day, try to take the treatment at 7am, 11am, 3pm, 7pm and 11pm.

Aciclovir tablets can be taken with or without food, but you should make sure you drink plenty of water to avoid kidney problems.

Swallow the tablets whole with at least one glass of water. If you have trouble swallowing these tablets whole, you can dissolve them in a glass of water; although you should make sure you drink the full glass of water, to take in all of the medicine.

What happens if I miss a dose?

If you have forgotten to take one of your doses of Aciclovir you can take it as soon as you remember. However, if this means you will be taking it at a time that is close to your next scheduled dosage, do not take the missed pill. You must not double dose on this medicine. Just skip the dose and continue your course schedule as recommended. If you have any worries concerning a forgotten tablet, contact your doctor or pharmacist.

What if I take too much?

If you accidentally take too much Aciclovir, you must contact your doctor or the emergency services straight away. Take any remaining tablets with you to your consultation.

Aciclovir is unlikely to cause you any harm if you accidentally double dose; however, as a precaution, we recommend speaking to your doctor or pharmacist if you fear that you have taken too much.

Aciclovir FAQ's

Can you buy Aciclovir tablets over the counter?

You must have a prescription to purchase this medicine over the counter. Your doctor will give you a prescription for Aciclovir tablets or cream if they deem it an appropriate treatment for you. If you are issued a prescription for the medication, you can buy it from a UK registered pharmacy over the counter.

Can I drink alcohol while I take it?

Yes, it is safe for you to drink alcohol while using this prescription medicine.

Can I have sex while I use these tablets?

If you have been given a prescription to take Aciclovir as a treatment for genital herpes, you should not have sex until your sores and blisters have healed completely. Even when your symptoms of genital herpes have cleared up, you should always use a condom when having sex. If you or your partner are using Aciclovir as a cold sore treatment, you should also avoid kissing and oral sex until the cold sores have healed completely. This will reduce the risk of passing on the cold sore virus to your partner.

What should I do if the treatment doesn't work?

If you complete the course of this prescription medicine and the treatment has not worked, you should go back to your doctor. Whatever this medicine is used to treat, if the symptoms get worse you should go back to your doctor as soon as possible; they may increase the dose of your treatment.

How do I order it online?

You can order this treatment online when you have been given a prescription by your doctor. Purchase Aciclovir tablets online at a UK registered pharmacy like Medicine Direct. After a consultation with one of our certified doctors, you will be given a prescription to purchase the tablets. If you place your order with us before 2pm, we are able to offer you next day delivery. We sell doses of Aciclovir 400mg tablets.

Will it affect my fertility?

Although often used to treat genital herpes, there is no evidence to suggest that antiviral medication such as this will affect the fertility of either men or women. If you are being treated for genital herpes, you should not have sex until your condition has been cleared.

Are there any lifestyle changes I can make to prevent cold sores or herpes?

Certain lifestyle changes can help to reduce the things that trigger herpes: Try to reduce your levels of physical and emotional stress, Avoid using sunbeds and use a lip balm that has SPF 15 or higher, Make sure you get enough sleep and eat a healthy and balanced diet.

Side Effects of Aciclovir

The common side effects of Aciclovir can be found on the main product page.

The below side effects are very rare, affecting less than 1 in every 1,000 people who use Aciclovir tablets. Nonetheless, you should go back to your doctor if you notice any of the below symptoms while using the treatment:

  • You are having fits
  • You have a reduced number of red blood cells (anaemia)
  • You have a reduced number of white blood cells (leukopenia)
  • You feel weak
  • You have paralysis in parts or all over your body
  • You feel agitated or confused
  • You have hallucinations
  • You have a reduced number of blood platelets (thrombocytopenia)
  • You are shaking or have tremors
  • You fall unconscious
  • You have jaundice (yellowing skin or whites of the eyes)
  • You have kidney problems, urinating less frequently
  • You have lower back pain or pain above your hip
  • You have hepatitis (inflamed liver)
  • You have a lack of coordination or are unsteady on your feet

In rare cases, it is also possible to suffer a severe allergic reaction to Aciclovir tablets.

If you experience any of these symptoms while using the treatment, you should either got to A&E or call 999 immediately. You might require immediate treatment in hospital:

  • You have a skin rash that is red, itchy, swollen, blistering or peeling
  • You are wheezing
  • You are finding it difficult to talk or speak
  • You have swelling of the mouth, tongue, face, throat or lips
  • You have tightness in the throat or chest

Always read the patient information leaflet before taking any prescription tablets.

Aciclovir Warnings and drug interactions

As with all prescription treatments, Aciclovir may interact with other medicines. This may also make you more vulnerable to side effects.

It is very important that you inform your doctor and pharmacist of any other medication you are already using before you start to take a new one. This includes both prescription and non-prescription medicine, herbal remedies, vitamins and supplements.

In particular, you should make sure your doctor is aware if you are currently taking:

  • A medicine to treat stomach ulcers called cimetidine
  • Medicines to treat asthma called aminophylline or theophylline
  • A medicine to treat gout called probenecid
  • A prescription medicine given after organ transplants called mycophenolate mofetil

There are various herbal medicines used to treat the likes of cold sores and genital herpes. You must inform your doctor if you are currently using any of these, before you start to use Aciclovir.

Only ever purchase this medicine when you have been given a prescription by your doctor; it should only be bought from pharmacies that are registered with the General Pharmaceutical Council (GPC), like Medicine Direct.

Because some of the common side effects associated with Aciclovir include feeling dizzy, stomach pain, having hallucinations or feeling tired, it is not advised that you drive or operate any machinery if you experience these effects. If you experience any of these side effects, you should not drive, ride a bike or operate machinery until you feel better. If these symptoms persist, go back and speak to your doctor.

This prescription medicine is suitable for children to take, although their dose will most likely be lower than an adult's.

Pregnancy and breastfeeding

Aciclovir is considered to be safe to take during pregnancy. If you experience regular breakouts, the doctor may recommend your taking Aciclovir during your pregnancy to prevent a possible breakout during childbirth, as this can pass the virus down to the newborn baby.

We recommend speaking to your doctor, who will be able to explain the risks and benefits of taking acyclovir during pregnancy.

Aciclovir is safe to use while breastfeeding. If you are taking Aciclovir tablets, some of the medication may make its way into the breast milk, but the amount is considered too small to present any harm to your baby.

It is important to speak to your doctor if you are currently breastfeeding and taking acyclovir tablets, they will be able to advise you on the best course of action for you and your baby.

You can find additional information on the BUMPS website.

Aciclovir Ingredients

Each tablet contains aciclovir as the active ingredient.

Other ingredients also contained in this medicine are: magnesium stearate, microcrystalline cellulose, sodium starch glycolate, pregelatinized starch and colloidal anhydrous silica.

Delivery Company Delivery Service Price Details
Royal Mail UK Delivery Standard UK Tracked £2.99 3 - 4 Working Day Delivery
DPD UK Next Day Delivery Next Day Delivery - Tracked £5.95 Order by 2pm (subject to Dr approval) Next Working Day Delivery
DPD UK Next Day Delivery Next Day Tracked Morning Delivery by 12:00pm £12.95 Next Working Day Morning Delivery by 12:00pm
DPD UK Next Day Delivery Tracked Saturday Delivery £9.95

Delivery specified for Saturday

Order Friday by 2pm (subject to Dr approval)

Please note that next day delivery to Northern Ireland, Scottish Highlands & Islands and British Isles cannot be guaranteed. Please contact our team for more information.

Written bySonia Khan MPharm: 2076091

Updated on: 04/06/2021

This content has been written by our Pharmacist Sonia Khan and has been medically reviewed by our Superintendent Pharmacist Hussain Abdeh

Sonia Khan
MPharm: 2076091


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