Aciclovir (also spelled acyclovir) is an antiviral medicine used in the UK to treat infections caused by viruses in the herpes family, including cold sores, genital herpes, shingles and chickenpox. This guide explains what aciclovir is, what the tablets are used for and how they are generally taken. It also covers common questions, such as whether you can take aciclovir with food, whether tablets can be crushed or halved, how doses should be spaced and whether aciclovir cream and tablets can be used together.
The information here is for general guidance and reflects information from the NHS and the licensed Summary of Product Characteristics (SmPC) published on the electronic Medicines Compendium (emc). It does not replace advice from your prescriber, who can advise you based on your individual circumstances.
What Is Aciclovir?
Aciclovir is an antiviral medicine, not an antibiotic. It works against certain viruses in the herpes family rather than bacteria. It is available in several forms, including tablets, dispersible tablets, 5% cream and eye ointment.
Aciclovir does not remove the virus from the body. Instead, it interferes with the virus's ability to multiply. This may help reduce symptoms and, depending on the infection and when treatment is started, may shorten the duration of an outbreak. Aciclovir is generally more useful when treatment is started early, so follow your prescriber's instructions about when to begin treatment.
What Are Aciclovir Tablets For?
Aciclovir tablets are used to treat and, in some cases, help prevent infections caused by herpes simplex and varicella zoster viruses. According to the NHS, aciclovir can be used for cold sores, genital herpes, shingles and chickenpox. It may also be prescribed to help prevent certain herpes infections in people with a weakened immune system.
In practice, aciclovir tablets may be prescribed for:
- Cold sores (herpes simplex around the lips and mouth), particularly when outbreaks are frequent or severe
- Genital herpes, for individual episodes and, in some cases, to help prevent recurrent outbreaks
- Shingles (herpes zoster)
- Chickenpox (varicella), in certain adults and people at higher risk of complications
- Prevention of certain herpes infections in people who are immunocompromised
The strength prescribed depends on the infection being treated and your individual circumstances. Strengths such as 200mg and 400mg are commonly used for herpes simplex infections, while 800mg is commonly used for shingles and chickenpox. Your prescriber will decide the appropriate strength, dose and treatment duration based on your diagnosis, kidney function and overall health.
How to Take Aciclovir Tablets
When aciclovir is prescribed, treatment is generally started as soon as possible after symptoms begin. For conditions such as cold sores and genital herpes, this may mean starting treatment when you first notice symptoms such as tingling, itching or burning, depending on your prescription and medical advice. Starting treatment early may make it more effective.
General administration points, based on NHS guidance and the SmPC, include:
- Swallow tablets with water, or use them as dispersible tablets if you have been prescribed that formulation. Follow the instructions supplied with your medicine.
- Drink plenty of fluids while taking aciclovir. This is particularly important with higher doses and for people who have reduced kidney function, because aciclovir is cleared through the kidneys.
- Space doses as evenly as possible throughout the day, following the instructions on your prescription. Try to take them at roughly the same times each day.
- Complete the course as prescribed, even if your symptoms start to improve. Do not stop treatment early unless your prescriber tells you to.
If you are also using aciclovir cream for a suitable skin infection, a thin layer of aciclovir 5% cream is generally applied to the affected area five times a day, approximately every four hours, following the product instructions. It is intended for external use and should not be applied inside the mouth, nose, eyes or vagina.
Aciclovir Dosing Schedule (Reference Information Only)
The table below summarises the licensed adult dosing schedule published in the emc Summary of Product Characteristics. It is provided as reference information to help you understand a prescription and is not a personal dosing recommendation.
Your prescribed dose and treatment length may be different. This is particularly important if you have kidney problems, a weakened immune system or other medical conditions. Always follow the instructions provided by your prescriber or pharmacist.
| Condition (adults) | Licensed schedule per the SmPC | Typical course |
|---|---|---|
| Herpes simplex — treatment | 200mg five times daily, about every 4 hours, omitting the night-time dose | 5 days |
| Herpes simplex — suppression (immunocompetent) | 200mg four times daily (every 6 hours) or 400mg twice daily (every 12 hours) | As directed |
| Herpes simplex — prevention (immunocompromised) | 200mg four times daily, about every 6 hours | As directed |
| Chickenpox and shingles — treatment | 800mg five times daily, about every 4 hours, omitting the night-time dose | 7 days |
Quick answer: how many hours apart? For standard five times a day schedules, doses are generally taken at approximately four hourly intervals during waking hours, with no dose usually needed overnight. A six times a day schedule with doses during the night is not part of the standard licensed regimen. Suppression regimens may use longer intervals, such as around six or twelve hours, depending on the prescribed schedule. Always follow the exact instructions on your prescription.
A note on missed doses, following NHS advice: take a missed dose as soon as you remember, unless it is nearly time for the next dose. In that case, skip the missed dose and continue with your usual schedule. Do not take a double dose to make up for a missed one.
Aciclovir 400mg: How to Take It
Aciclovir 400mg tablets are commonly prescribed for herpes simplex infections. Within the licensed dosing schedules, 400mg twice daily, approximately twelve hours apart, may be used to suppress recurrent herpes simplex in people with a normal immune system. Treatment of an active episode may instead use the 200mg five times a day schedule.
Because 400mg can be prescribed for different reasons, including treating an active infection or reducing recurrences, the exact instructions on your prescription are what matter. Take each dose with water and try to keep the doses evenly spaced according to your prescribed schedule.
Aciclovir 800mg: How to Take It
Aciclovir 800mg tablets are commonly associated with the treatment of shingles and chickenpox. The licensed schedule for these infections is 800mg five times a day at approximately four hourly intervals during waking hours, with the night time dose omitted, usually for seven days.
For shingles, starting treatment within 72 hours of the rash appearing is generally recommended because treatment is more likely to be helpful when started early. Your prescriber can advise you on the appropriate timing based on your symptoms.
Drink plenty of fluids throughout the day while taking aciclovir, particularly when taking higher doses. This is important because aciclovir is cleared through the kidneys.
Should You Take Aciclovir With or Without Food?
This is one of the most common questions, so here is the simple answer.
Aciclovir can be taken with or without food. NHS guidance states that you can eat and drink normally while taking aciclovir, and the licensed product information does not require the tablets to be taken at a particular time in relation to meals. You do not need to take it on a full stomach, so taking it on an empty stomach is also fine if that suits you.
Some people may find that taking aciclovir with a little food feels more comfortable if they experience mild nausea, which is a possible side effect. However, food is not required for the medicine to work. Drinking enough water and following the prescribed dosing schedule are more important.
Can You Crush, Break or Disperse Aciclovir Tablets?
Swallowing tablets can be difficult for some people, so these questions are understandable.
Dispersing in water: The Summary of Product Characteristics (SmPC) for standard aciclovir tablets states that they may be dispersed in a minimum of 50ml of water or swallowed whole with a little water. NHS guidance also explains that aciclovir tablets can be dissolved in water before drinking. If you have difficulty swallowing tablets, this can be a useful option, provided it is suitable for the specific product you have been prescribed.
Crushing or breaking in half: Standard aciclovir tablets are generally intended to be swallowed whole or dispersed in water. Do not crush or split them unless your pharmacist or prescriber has confirmed that your particular tablets can be handled this way. Not all aciclovir tablets are scored for splitting, and breaking a tablet may not give you an accurate dose.
This is particularly important if you have kidney problems, as your prescriber may need to adjust your aciclovir dose.
Important: Do not crush aciclovir tablets and apply the powder to your skin. Tablets and creams are formulated differently. For infections where topical treatment is appropriate, use the prescribed aciclovir 5% cream according to the product instructions.
Taking aciclovir at evenly spaced intervals throughout the day: Follow the schedule provided by your doctor or pharmacist and try to take each dose at the recommended interval. Keeping to the prescribed schedule helps you take the medicine consistently. Do not take extra doses because you think the medicine is not working quickly enough.
If you miss a dose: Take it as soon as you remember, unless it is nearly time for your next dose. If your next dose is due soon, skip the missed dose and continue with your normal schedule. Do not take two doses together to make up for a missed dose.
If you think you have taken more aciclovir than prescribed, seek medical advice promptly.
Interactions with other medicines: Certain medicines may interact with aciclovir and may increase the risk of side effects or affect how the medicine is processed by the body. Always tell your doctor, prescriber or pharmacist about any other medicines you are taking before starting aciclovir, including over-the-counter drugs and herbal supplements.
Can You Use Aciclovir Cream and Tablets Together?
Aciclovir cream and tablets may sometimes be used at the same time if advised by a prescriber or pharmacist. In practice, tablets are the mainstay for anything beyond a mild, occasional cold sore, and cream may sometimes be used alongside them to treat local symptoms. Because each product has its own instructions, only combine them if your prescriber or pharmacist has advised it, and follow the directions for each separately. Do not use more than directed in the hope of improving symptoms more quickly — using more does not make aciclovir work better and can increase side effects.
Always tell your doctor about any other medicines you are taking, as some may interact with aciclovir tablets.
While taking aciclovir tablets, it is generally recommended to drink plenty of fluids, particularly when taking higher doses. Common side effects can include headache, nausea, dizziness and tiredness. Although uncommon, serious side effects can occur. Always read the patient information leaflet and seek medical advice if you develop concerning symptoms. If you experience these, seek medical advice promptly.
In the UK, you cannot buy aciclovir tablets over the counter; they require a prescription from a healthcare professional. However, aciclovir may be available following an online consultation with an appropriately qualified prescriber, subject to clinical suitability. If treatment is considered appropriate, medication may be prescribed, dispensed and delivered to your chosen address.
For further guidance on managing herpes infections, including how to treat genital herpes and cold sores, and information on outbreak treatment options, consult your doctor or a sexual health clinic. Always follow their advice carefully to ensure safe and effective treatment.
Tablets or Cream? A Quick Comparison
| Feature | Aciclovir tablets | Aciclovir 5% cream |
|---|---|---|
| Best suited to | Frequent, severe or widespread herpes outbreaks; shingles; chickenpox; genital herpes | Local treatment of cold sores |
| How it works | Acts throughout the body | Acts on the surface of the treated skin |
| Typical use pattern | Several doses a day for a set course | Thin layer five times a day, about every 4 hours |
| Needs a prescription assessment | Yes | Available over the counter for cold sores, or via assessment |
| Starting point | At first symptoms | At first tingle |
Neither form is universally better. The right option depends on the type of infection, your symptoms and your individual circumstances. If you have a weakened immune system, frequent recurrences or symptoms affecting areas beyond the lips, speak to a healthcare professional for advice.
Who Should Be Careful With Aciclovir
Aciclovir is generally well tolerated, but tell your prescriber before starting treatment if you have kidney problems, are pregnant or breastfeeding, are dehydrated, or have previously had an allergic reaction to aciclovir, valaciclovir, famciclovir or penciclovir.
People with reduced kidney function may need a lower dose and may be advised to pay particular attention to staying well hydrated. Your prescriber can take these factors into account when deciding whether aciclovir is suitable and which treatment is appropriate.
How to Get Aciclovir in the UK
Aciclovir 5% cream for cold sores is available from pharmacies without a prescription, while aciclovir tablets are prescription only. Through a registered online pharmacy such as EverydayMeds, the process may include:
- You complete a short online health assessment covering your symptoms, medical history and any medicines you take.
- An independent prescriber reviews your answers to assess whether treatment is suitable and which option may be appropriate.
- If treatment is approved, your medicine is dispensed by a GPhC registered pharmacy and sent with tracked UK delivery.
- Medication is supplied through regulated UK supply channels, with pricing and payment details shown before you place your order.
You can complete an online assessment for cold sore treatment where appropriate, and returning customers can log in to reorder. Availability may vary, so check the website for the latest information before placing an order.
Aciclovir Pricing at EverydayMeds
The figures below are the standard prices displayed on the EverydayMeds website. The final price is confirmed at checkout after your assessment, and the exact product supplied will depend on the prescriber's clinical assessment and recommendation.
| Treatment | Standard price |
|---|---|
| Aciclovir tablets | From £12.99 |
| Aciclovir 5% cream | From £8.99 |
| Valaciclovir | From £18.99 |
| Valtrex (branded valaciclovir) | From £34.99 |
Valaciclovir is a related antiviral that the body converts into aciclovir; it is sometimes chosen because it can be taken fewer times a day. Whether it suits you is, again, a matter for your prescriber.
Storage and Everyday Tips
Keep aciclovir tablets in their original packaging and store them at room temperature, away from excessive heat and moisture and out of reach of children. Follow the storage instructions on the carton for aciclovir cream.
If you sometimes forget doses, a phone reminder may help you stay on schedule. Taking each dose with a glass of water can also make it easier to remember to drink enough fluids throughout the day.
Key Takeaways
- Aciclovir is an antiviral medicine used for infections caused by viruses in the herpes family. It can help control outbreaks but does not remove the virus from the body. Starting treatment early may make it more effective.
- Aciclovir can be taken with or without food, so taking it on an empty stomach is fine.
- Standard tablets may be dispersed in at least 50ml of water or swallowed whole with water. This can be useful if you have difficulty swallowing tablets.
- Do not crush tablets and apply them to the skin. Use the licensed 5% cream when a topical treatment is appropriate.
- Standard five times a day treatment schedules use doses approximately four hours apart during waking hours, with the night time dose omitted. Suppression schedules use longer intervals.
- Your prescriber decides your exact dose and treatment duration based on your condition and individual circumstances.
Medical Disclaimer
This article provides general information and patient education about aciclovir. It does not constitute medical advice, a diagnosis or a personal treatment recommendation.
The dosing schedules mentioned are based on licensed information published in the electronic Medicines Compendium and are included to help explain how aciclovir may be prescribed. They are not instructions to self treat. Aciclovir tablets are prescription only medicines, and their suitability depends on an individual clinical assessment.
Always follow your prescriber's instructions and read the patient information leaflet supplied with your medicine. Speak to a qualified healthcare professional if your symptoms are severe, spreading, affecting the area around the eyes or not improving as expected. You should also seek medical advice if you are pregnant, breastfeeding, immunocompromised or have kidney problems.
If you think you have taken too much aciclovir or are concerned about a serious reaction, seek urgent medical advice. In an emergency, call 999.
