Aciclovir

Legal status and availability in the UK

Aciclovir tablets, suspension and infusion are prescription-only medicines (POM) in the UK; aciclovir 5% cold sore cream is available from pharmacies without a prescription.

In our online pharmacy, aciclovir is available without a prescription, with discreet delivery to the United Kingdom in 9–21 days.

Basic aciclovir information

• INN (international nonproprietary name): Aciclovir
• Brand names available in the United Kingdom: Zovirax, Aciclovir (generic)
• ATC code: J05AB01
• Forms & dosages: Tablets 200mg, 400mg and 800mg; cream 5%; suspension 200mg/5ml; intravenous vials 250mg, 500mg and 1000mg
• Manufacturers in the United Kingdom: GlaxoSmithKline, Sandoz, Mylan, Sun Pharma and other generic manufacturers
• Registration status in the United Kingdom: Prescription only (tablets, suspension, infusion); 5% cold sore cream available without a prescription
• OTC / Rx classification: Rx — prescription only (oral and intravenous forms)

Aciclovir has remained a mainstay antiviral in UK practice because it is familiar, widely stocked and clinically dependable for herpes simplex, herpes zoster and varicella.

Benefit is clearest when treatment is started early, especially for cold sores and shingles, where prompt treatment can shorten symptom time and reduce lesion progression.

The medicine is listed as J05AB01 for systemic use, while topical dermatological forms sit under D06BB, which matches the way pharmacists and prescribers separate tablet and cream use in practice.

In the UK, Zovirax and generic aciclovir remain the best-known names, with oral tablets in 200mg, 400mg and 800mg strengths and cream at 5%.

Use by route at a glance

Oral aciclovir remains prescription-only in the UK.

How effective aciclovir is in NHS practice

Patients usually want one simple answer: will it actually make the outbreak better?

In routine NHS care, aciclovir is valued because it often reduces pain, shortens the duration of an episode and helps lesions settle sooner, particularly when treatment begins promptly.

For cold sores, people often notice the biggest benefit when the tablets or cream are started at the tingling stage rather than after the blister has fully formed.

For shingles, early oral treatment is important because the medicine is most helpful in the first phase of the rash and nerve pain.

Key points

• What patients notice first: less burning, less pain and a shorter flare.
• Where benefit is modest: late-start topical treatment and long-standing lesions.
• Suppressive treatment: fewer recurrences in people with repeated genital herpes outbreaks.
• Hospital use: intravenous treatment is reserved for severe infections and specialist care.

In the UK, oral aciclovir is prescription only and is supplied against a valid prescription.

Real-world formats include tablets, cream, suspension and IV vials, which helps clinicians match the formulation to the patient, whether that is an adult with recurrent herpes or a child needing suspension.

Indications, approved uses and common off-label requests

People often ask for aciclovir for much more than a one-off cold sore, so it helps to separate the licensed uses from the requests that need specialist oversight.

In UK practice, the evidence-based indications are herpes labialis, genital herpes, herpes zoster and varicella.

Some patients also ask about prevention, frequent recurrences or use in immunocompromised people, but those situations need individual assessment and sometimes specialist input.

Definitions

Cold sores

Herpes labialis, usually treated early with topical cream or oral tablets when appropriate.

Genital herpes

HSV infection of the genital area, treated for initial episodes, recurrences or suppression.

Shingles

Herpes zoster, where oral treatment is most useful when started quickly after the rash appears.

Chickenpox

Varicella, where treatment is generally started within 24 hours of the rash.

Standard regimens from the product data include 200mg five times daily for HSV or initial genital herpes, 400mg twice daily for suppression, and 800mg five times daily for shingles.

For recurrent genital herpes, treatment may be used for a shorter course or longer suppression, depending on how often outbreaks happen.

Brand names, formulations and United Kingdom product landscape

In the UK, the same core medicine appears in both branded and generic forms.

Zovirax is the best-known brand, while generic aciclovir is widely available across community and hospital settings.

Different formulations matter because a child, a patient with shingles and someone with a cold sore do not all need the same product.

For a simple UK comparison, patients usually only need to know whether they are getting tablets, cream or suspension, and whether the dose matches the problem being treated.

Contraindications, cautions and who needs extra monitoring

Most people tolerate aciclovir well, but it is not suitable for everyone.

The main absolute contraindication is hypersensitivity to aciclovir, valaciclovir or any excipient in the formulation.

Certain groups need extra care because the medicine is cleared by the kidneys and can build up if kidney function is reduced.

• People with renal impairment.
• Older adults, especially if frail or dehydrated.
• Patients with neurological disorders or a history of confusion.
• Anyone taking other nephrotoxic medicines.
• Pregnant or breastfeeding patients who want treatment advice from a GP, pharmacist or NHS 111.

Practical UK advice matters here: if dizziness or confusion appears, driving should be avoided until a clinician has checked what is going on.

Alcohol is not a direct interaction, but it can make dehydration more likely and may also lead to missed doses.

Dosage guidance for adults, children and renal impairment

Correct dosing is where aciclovir works best, because the same medicine is used for short outbreaks, suppression and more serious infections.

Most UK-style regimens follow the indication rather than a single fixed dose for everyone.

Adults with herpes simplex or genital herpes usually take 200mg five times daily for 5 to 10 days.

Suppressive treatment for recurrent genital herpes is often 400mg twice daily, while shingles is typically treated with 800mg five times daily for 7 to 10 days.

For chickenpox, treatment should be started within 24 hours of the rash for best effect.

Children are dosed by body weight, and the suspension is especially useful for infants and small children who cannot swallow tablets.

Severe renal impairment may require the dosing interval to be extended, and intravenous treatment should only be used under hospital supervision.

Side effects, overdose and Yellow Card reporting

Side effects are usually mild, but patients should still know what is expected and what needs urgent review.

Common adverse effects include nausea, vomiting, diarrhoea, headache, dizziness, tiredness, skin irritation and a mild rash with cream.

Confusion is less common and is seen more often in older adults or people with kidney impairment.

Key points

• Common: nausea, headache, dizziness, tiredness and local skin irritation.
• Less common but important: confusion, especially with poor kidney function.
• Urgent overdose signs: agitation, confusion, lethargy and renal dysfunction.
• Severe cases: IV fluids and sometimes haemodialysis may be needed.

Because aciclovir is cleared through the kidneys, dehydration and overdose can make problems worse very quickly.

That is why the MHRA Yellow Card scheme matters: it helps track rare reactions and keeps UK pharmacovigilance useful for patients and prescribers.

Interactions with medicines, food, drink and daily habits

Most people do not need to change what they eat, but hydration is important.

The biggest interaction concern is not food, tea or coffee, but other medicines that can affect the kidneys.

That includes nephrotoxic drugs, diuretics and some medicines used in complex long-term treatment plans.

• Tell the pharmacist about all prescribed medicines.
• Mention over-the-counter painkillers as well, especially if you use them regularly.
• Say if you take diuretics or medicines that can affect kidney function.
• Ask if another antiviral has been suggested and whether the dosing is different.

Alcohol does not have a direct chemical interaction, but it can make dehydration worse and increase the chance of missed doses or stomach upset.

For most patients, the practical advice is simple: drink enough, take doses on time and ask before combining treatment with other medicines.

Comparable medicines and when prescribers may choose alternatives

Aciclovir is not the only antiviral used for herpes infections, and sometimes another medicine fits the patient better.

Valaciclovir, famciclovir and penciclovir sit in the same broad treatment space, but each has its own strengths and weaknesses.

Pros and cons

• Aciclovir: long experience and multiple formulations.
• Aciclovir: needs more frequent dosing than valaciclovir.
• Valaciclovir: simpler dosing because oral bioavailability is better.
• Famciclovir: useful alternative with similar indications.
• Penciclovir: topical option for selected cold sore use.

NHS formulary habits often favour aciclovir because it is well known and available in several forms.

Clinicians may still choose an alternative if adherence is a concern, if dosing convenience matters or if a patient prefers a different regimen.

How to use aciclovir properly and what patients should ask next

The best results come from starting early, taking the full course and keeping doses on schedule.

Missing doses can reduce the benefit, and doubling up is not the answer.

Adults should take a missed dose as soon as they remember if it is only a few hours late.

If it is nearly time for the next dose, the missed one should be skipped and the normal schedule continued.

Practical counselling points

• Start treatment as soon as symptoms begin.
• Complete the prescribed course, even if the rash looks better.
• Do not double doses after a missed tablet.
• Keep well hydrated, especially in hot weather or if unwell.
• Store tablets and cream at room temperature, usually under 25°C.

Overdose can cause agitation, confusion, lethargy and renal dysfunction, so urgent help is needed if too much has been taken.

Patients should ask a pharmacist or GP if they are pregnant, breastfeeding, have kidney disease, get repeated outbreaks or have eye involvement.

It is also sensible to seek official information from NHS patient pages or the medicine leaflet before starting treatment.

Delivery across the United Kingdom