You can significantly reduce your risk of getting herpes from a partner who has it by combining a few strategies: using condoms consistently, having your partner take daily antiviral medication, and avoiding sex during outbreaks and the warning signs that precede them. No single method eliminates the risk entirely, but layering these precautions together makes transmission uncommon.
Why Herpes Spreads Even Without Symptoms
The biggest challenge with herpes prevention is that the virus doesn’t need a visible sore to spread. The virus periodically reaches the skin’s surface and becomes contagious even when a person looks and feels completely fine. This is called asymptomatic shedding. In a study published in the New England Journal of Medicine, more than half of women with genital HSV-2 shed the virus without any visible lesions during a roughly three-and-a-half-month follow-up period. On average, shedding happened on about 2% of days. That’s a small percentage, but it’s unpredictable, and it means there’s no guaranteed “safe” window based on appearance alone.
This is why relying solely on avoiding sex during outbreaks isn’t enough. A real prevention plan accounts for the possibility that the virus is present even when everything looks normal.
How Much Condoms Help
Condoms are one of the most effective single tools you have, but their protection varies depending on the direction of transmission. Research on couples where one partner had HSV-2 found that condoms reduced per-act transmission from men to women by 96%, and from women to men by 65%. The difference comes down to anatomy: condoms cover the primary site where men shed the virus, but women can shed from skin areas a condom doesn’t reach.
Condoms still matter in both directions. Even 65% reduction per sexual encounter adds up to substantially lower risk over time. The key is consistency. Using condoms most of the time offers far less protection than using them every time, because a single unprotected encounter during an asymptomatic shedding day is all it takes.
For oral sex, the same logic applies. HSV-1, the type that commonly causes cold sores, can spread from the mouth to the genitals during oral sex. Using a barrier (a condom for oral sex on a penis, a dental dam for oral sex on a vulva) reduces that risk.
Daily Antiviral Medication
When the partner who has herpes takes a daily antiviral, it cuts the amount of virus they shed and roughly halves the chance of passing it on. In an eight-month study of couples where one partner had HSV-2 and the other didn’t, transmission occurred in 3.6% of couples using a placebo versus 1.9% of couples where the infected partner took daily medication. That’s a 48% reduction in transmission risk.
This is suppressive therapy, meaning the medication is taken every day regardless of whether symptoms are present. It works by keeping viral activity low, which reduces both the frequency and severity of outbreaks and the amount of invisible shedding between them. Your partner can talk to their doctor about whether this approach makes sense for your situation.
Avoiding Sex During Outbreaks and Warning Signs
Transmission risk is highest when sores are present, so skipping sex during an active outbreak is essential. But the window of higher risk actually starts before sores appear. Many people experience prodromal symptoms, early warning signs that signal the virus is becoming active. These include tingling, itching, or burning at the usual outbreak site, as well as shooting pain in the legs, hips, or buttocks. Once your partner notices any of these signs, avoid skin-to-skin contact in the affected area until the outbreak has fully healed.
Both of you should know what your partner’s outbreaks typically look like, where they occur, and what their early warning signs feel like. The more familiar your partner is with their own pattern, the earlier they can flag it.
Combining Methods for Maximum Protection
Each of these strategies works on its own, but they’re most powerful together. Condoms reduce per-act risk. Daily antivirals reduce the amount of virus available to transmit. Avoiding sex during outbreaks and prodromal symptoms removes the highest-risk days from the equation entirely. When you stack all three, the overall transmission risk drops to a level that many couples find manageable for years or even indefinitely.
To put this in perspective: in the antiviral study, only about 2 in 100 couples saw transmission over eight months with medication alone, without requiring condom use. Add consistent condoms on top of that and the numbers get smaller still.
Oral Herpes and Genital Transmission
Many people focus on genital-to-genital transmission, but oral herpes (typically HSV-1) is a common source of genital infections through oral sex. Someone with a history of cold sores can pass HSV-1 to a partner’s genitals, especially during or just before an oral outbreak. The same shedding principle applies: the virus can be present on the lips or in the mouth without a visible cold sore.
If your partner gets cold sores, avoid receiving oral sex when they have a sore or feel tingling on their lips. Using barriers during oral sex reduces this risk further. It’s worth noting that genital HSV-1 tends to recur less frequently than genital HSV-2, but the initial infection can still be significant.
What About Supplements and Diet?
You may have heard that the amino acid lysine can help prevent outbreaks. The research here is mixed. A review of the clinical evidence found that lysine at doses under 1 gram per day showed little meaningful benefit unless combined with a diet low in arginine (an amino acid found in nuts, chocolate, and seeds). At 3 grams per day, one trial did show a statistically significant reduction in outbreak frequency. Some smaller studies at around 1 gram daily found modest benefits for some participants but not others.
The bottom line: lysine may modestly reduce outbreak frequency for some people at higher doses, but it’s not reliable enough to serve as a primary prevention strategy. It’s something your partner might consider alongside proven methods like antivirals and condoms, not instead of them.
Getting Tested
If you’re in a relationship with someone who has herpes and want to know your own status, a blood test can check for HSV antibodies. One important detail: after a potential exposure, current tests can take up to 16 weeks to accurately detect an infection. Testing earlier than that may produce a false negative. If you’ve recently started a sexual relationship with someone who has herpes, waiting at least four months before testing gives the most reliable result.
Knowing your own status matters because many people already carry HSV-1 or HSV-2 without knowing it. If you already have the same type your partner has, your risk of getting a new infection from them is very low, since your body already produces antibodies against that strain.
Open Communication Makes Prevention Work
All of these strategies depend on honest, ongoing conversation between partners. Your partner needs to feel comfortable telling you when they notice prodromal symptoms or an outbreak starting, even if the timing is inconvenient. You need to be able to discuss condom use, medication, and testing without shame or blame. Couples who treat herpes prevention as a shared project rather than one person’s problem tend to stick with their prevention plan more consistently, and consistency is what drives the numbers down.
Herpes is extremely common, and the tools for preventing transmission are well-studied. The risk can’t be reduced to zero without abstaining from contact entirely, but for most couples who use condoms, antivirals, and outbreak awareness together, transmission remains uncommon over long periods of time.