Get frequent genital herpes outbreaks? There's an approach that goes beyond treating each flare-up as it comes.
Suppressive therapy means taking a low dose of an antiviral, such as aciclovir or valaciclovir, every day. It helps prevent outbreaks, reduces how much of the virus you shed, and lowers the risk of passing herpes to a partner.
This guide covers who it suits best, what the evidence shows and what to expect from taking a daily antiviral for herpes long term.
Suppressive therapy is about prevention. Instead of reacting to each outbreak, you take a small daily dose to stop them happening.
What is suppressive therapy and how does it work?
Genital herpes is caused by the herpes simplex virus (HSV). After the first infection, the virus stays dormant in your body and can wake up again to cause repeat outbreaks.
If you get frequent outbreaks, taking an antiviral every day, rather than only during an outbreak, is worth considering. This is called suppressive therapy, and it's one of the two main ways to manage genital herpes long term.
The two antivirals used for suppressive therapy in the UK are aciclovir and valaciclovir. Both stop the virus from copying itself, keeping the amount of virus low enough to prevent most outbreaks.
Valaciclovir is turned into aciclovir in your body. Its advantage is that it's absorbed more efficiently, so a smaller dose taken less often has a similar effect.
Who should consider genital herpes suppression treatment?
Suppressive therapy isn't necessary for everyone with genital herpes. It's most relevant if:
- You're having six or more outbreaks a year
- Your outbreaks are severe, long-lasting or causing you a lot of distress
- Your partner doesn't have herpes and you want to lower the risk of passing it on
- Outbreaks are affecting your mental health, relationships or quality of life
Guidelines from the British Association for Sexual Health and HIV (BASHH) say that deciding when to start suppressive therapy is a personal decision you make with your clinician. Your relationship and how much outbreaks affect your daily life should all be part of it.1
What doses are used?
The standard suppressive doses in the UK, for people who get six or more outbreaks a year, are:
- Aciclovir - 400mg twice a day (or 200mg four times a day)
- Valaciclovir - 500mg once a day (for people with up to ten outbreaks a year)
If standard doses don't give you enough control, your clinician may adjust your dose or switch you to the other medicine, as how well people absorb aciclovir varies.2
Same time, every day. Linking your tablet to something you already do, like brushing your teeth, makes it easier to remember.
These are prescription-only medicines, so you'll need a consultation to get them. Pharmica offers online consultations for both aciclovir and valaciclovir, with discreet delivery once prescribed.
How effective is suppressive therapy?
The evidence for suppressive therapy is well established. Clinical studies show that taking an antiviral every day cuts how often outbreaks happen by 70 to 80% in people who used to get them frequently.1
Suppressive therapy also reduces viral shedding. That includes shedding with no symptoms between outbreaks, when there's nothing visible but the virus can still be passed on. Aciclovir and valaciclovir have been shown to suppress shedding, with and without symptoms, by 80 to 90%.2
What about passing it on? A landmark trial published in the New England Journal of Medicine in 2004 involved 1,484 couples where one partner had HSV-2. It found that once-daily valaciclovir cut the risk of the other partner catching herpes by 48%, and the risk of them getting symptomatic genital herpes by 75%.3
Worried about telling a partner? A sexual health clinic can offer advice and support, as well as testing.
Suppressive therapy reduces the risk of passing herpes on, but it doesn't remove it completely. Using condoms alongside your daily medicine gives you the most protection.
How long do you take it for?
Suppressive therapy is usually recommended for at least six months to start with. After twelve months of continuous treatment, BASHH guidance recommends a review, to see whether your circumstances have changed and whether you'd like to try stopping.1
Some people find their outbreaks have become less frequent over time and they no longer need daily medicine. Others choose to carry on long term.
Some people get an outbreak soon after stopping. So it's sensible to plan the timing with your prescribing clinician, and keep a short course of episodic treatment to hand.
Do not stop suppressive therapy without a plan. Keep an episodic course to hand in case an outbreak follows.
Long-term suppressive therapy with aciclovir and valaciclovir has a good safety record. Studies of up to 24 months show few side effects, with headache, nausea and diarrhoea reported at similar rates to placebo. Healthy adults without kidney problems don't usually need routine blood tests.
Suppressive therapy vs episodic treatment
Episodic treatment means only taking antivirals when an outbreak happens, usually for two to five days, to make it shorter and milder. It's a reasonable choice if your outbreaks are infrequent and mild.
Suppressive therapy is the better option if your outbreaks are frequent, unpredictable or having a big impact on your daily life.
One practical point: episodic treatment works best when you start it within 24 hours of the first symptoms, like tingling or itching. If your outbreaks come on quickly, or you'd rather not deal with them as they happen, a daily tablet takes that pressure away.
Practical tips for taking suppressive therapy
- Take it at the same time each day - consistent timing helps keep steady levels of the medicine in your body.
- Don't double up if you miss a dose - take it as soon as you remember, unless it's nearly time for your next dose.
- Combine it with safer sex - condoms lower the risk of passing herpes on even further, and work well alongside daily medicine.
- Mention your other medicines - aciclovir can interact with some medicines, including mycophenolate mofetil, which is used after transplants. Always tell your GP or pharmacist what else you take.
- If you're still getting outbreaks - don't assume the medicine isn't working without speaking to your clinician first. Your dose may just need adjusting.
When to seek further advice
Contact your GP or a sexual health clinic if you:
- Are still having outbreaks despite taking suppressive therapy
- Develop new or unusual symptoms that could indicate a complication
- Are pregnant or planning to become pregnant, as specific guidance applies
- Have a weakened immune system, as standard suppressive doses may not be sufficient
- Experience side effects that are persistent or concerning
- Want to reassess whether to continue or stop treatment after twelve months
A full list of known side effects and interactions is available in the patient information leaflet supplied with your medication.
Frequently asked questions
Can you still transmit herpes while on suppressive therapy?
Yes, though the risk is significantly reduced. Suppressive therapy doesn't eliminate asymptomatic viral shedding entirely, it suppresses it. The landmark NEJM 2004 trial found that once-daily valaciclovir reduced the risk of transmission by around 48% in couples where one partner had HSV-2.2 For the most comprehensive protection, combining daily antiviral medication with condoms is recommended, as the two approaches work together.
Do you have to take herpes medication every day for it to work?
Yes, that's the core principle of suppressive therapy. Unlike episodic treatment, which is taken reactively during an outbreak, suppressive therapy only works if taken consistently every day. Missing doses can allow viral replication to increase and may reduce the protection it provides. Taking your tablet at the same time each day makes it easier to stay consistent.
How do you know if suppressive therapy is working?
The clearest sign is a significant reduction in the frequency of outbreaks. Most people on suppressive therapy experience far fewer recurrences than before, and some have none at all during treatment. If you're still having regular outbreaks after several weeks on the standard dose, speak to your clinician, as your dose may need reviewing or increasing.
Can suppressive therapy reduce herpes recurrence triggers?
Suppressive therapy works by keeping viral replication consistently low, which means common triggers such as stress, illness, or UV exposure are less likely to tip the balance into a full outbreak. It doesn't eliminate the underlying triggers themselves, but it raises the threshold at which they're able to cause a recurrence. Managing lifestyle factors alongside medication remains worthwhile.
Is there a daily medication for herpes available on the NHS?
Yes. Both aciclovir and valaciclovir are available on NHS prescription for suppressive therapy. Your GP or a sexual health clinic can assess whether you meet the criteria and prescribe accordingly. They're also available through regulated online pharmacies such as Pharmica following an online consultation, which some people find more convenient.
What happens when you stop suppressive therapy?
Outbreaks may return as the virus is no longer being suppressed. There can be a rebound outbreak within a few days of stopping, so BASHH guidance recommends planning this with your clinician and having episodic treatment available just in case.1 After stopping, it's worth monitoring your pattern of recurrences for two or more outbreaks before deciding whether to restart. Many people find their recurrence frequency has naturally declined over time.
References
- Patel R, et al. British Association for Sexual Health and HIV (BASHH). UK national guideline for the management of anogenital herpes. International Journal of STD & AIDS. 2024. doi:10.1177/09564624241282396
- 2024 European guidelines for the management of genital herpes. Journal of the European Academy of Dermatology and Venereology. 2025. PMC11934026
- Corey L, Wald A, Patel R, et al. Once-daily valacyclovir to reduce the risk of transmission of genital herpes. New England Journal of Medicine. 2004;350(1):11-20. doi:10.1056/NEJMoa035144
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.