References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Valtrex is the brand name for valaciclovir, an antiviral medication used to treat genital herpes, cold sores (oral herpes), and shingles. It works by stopping the herpes simplex virus from multiplying, which shortens outbreaks and reduces their severity. Valaciclovir is a prodrug of aciclovir, meaning the body converts it to aciclovir after absorption, but it has better oral bioavailability (you need fewer doses per day).
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What Does Valtrex Treat?
| Condition | Dosage | Duration |
|---|---|---|
| First genital herpes outbreak | 500mg twice daily | 5-10 days |
| Recurrent genital herpes | 500mg twice daily | 3-5 days |
| Suppressive therapy (frequent outbreaks) | 500mg once daily | Ongoing (6-12 months, then review) |
| Cold sores | 2g twice daily | 1 day |
| Shingles | 1g three times daily | 7 days |
Valtrex vs Aciclovir
| Feature | Valtrex (valaciclovir) | Aciclovir |
|---|---|---|
| Dosing | 1-2 times daily | 3-5 times daily |
| Bioavailability | ~55% | ~15-20% |
| Convenience | Higher (fewer doses) | Lower (more frequent) |
| Effectiveness | Equal | Equal |
| Cost | Higher | Lower (generic widely available) |
Both drugs are equally effective. Valtrex is preferred for its simpler dosing schedule. Aciclovir is cheaper and available in more formulations.
Side Effects
- Headache (most common)
- Nausea
- Abdominal pain
- Dizziness
- Very rarely: confusion, kidney problems (mainly at high doses or with kidney impairment)
Stay well hydrated while taking valaciclovir to support kidney function.
Where to Get Valtrex in the UK
- Sexual health clinic: Free prescription
- GP: Prescription after diagnosis
- Online prescription services: After consultation
- Generic valaciclovir is significantly cheaper than branded Valtrex and equally effective
Read more: Aciclovir | Genital herpes guide
Frequently Asked Questions
Does Valtrex cure herpes?
No. Valtrex manages herpes by suppressing viral replication. It shortens outbreaks, reduces severity, and (with daily suppressive therapy) reduces the frequency of recurrences and the risk of transmission. The virus remains dormant in the body permanently.
Can I take Valtrex long-term?
Yes. Daily suppressive therapy with valaciclovir is safe for long-term use. Many people take it for years. Your doctor will review periodically (usually every 12 months) to assess whether continued suppression is needed.
Can I buy Valtrex over the counter?
No. Valaciclovir requires a prescription in the UK. Aciclovir cream for cold sores is available over the counter, but oral antivirals (tablets) need a prescription.
Related reading
- Can You Get Herpes From a Toilet Seat?
- Can You Get Herpes From Kissing?
- Comprehensive Test: Chlamydia, Gonorrhoea and Herpes
- Cold Sores vs Syphilis Sores: How to Tell the Difference
- Genital Warts vs Herpes: What's the Difference?
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
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