I just had this same question and wanted to know more so I dove deep on this, here was my strategy based on lots of manual searching. Happy to share research if it's of interest to people. I was doing this as I had a STD free woman I was very interested in and we were trying to make it work.... we are still friends but she couldn't get past this, which I understand. I asked Claude for a detailed analysis:
I want you to analyze like a doctor providing medical advice to clients that are a discordant couple, the male having HSV2 the female does not. Look for medical websites and or research that would suggest if it is safe for them to engage in oral sex when the positive partner is taking suppressive therapy and is not experiencing a breakout. Exclude sites that do not have an association with reliable medical sources. Exclude advice suggestion, dental dams, or condom use as the couple does not want to go down that route together. Now expand this search to suggest if the female were to get oral HSV-2 what the frequency and severity of the infection would likely be. Does acquiring HSV-2 provide her immunity to genital hsv-2 and or oral hsv-1.
Part 1: Risk of HSV-2 Transmission via Oral Sex from a Male on Suppressive Therapy Without Active Outbreak
The scenario here is the male partner performing oral sex on the female (which wouldn't expose her to genital viral shedding) or the female performing oral sex on him (which would involve oral contact with his genital area). The key risk pathway is the female's oral mucosa contacting the male's genital skin where HSV-2 resides.
Suppressive therapy's effect on shedding: The landmark NEJM trial by Corey et al. found that valacyclovir reduced genital HSV-2 DNA detection from about 10.8% of days down to 2.9% of days New England Journal of Medicine. A later study confirmed that valacyclovir 1g once daily significantly reduced viral shedding by 78% compared to placebo PubMed Central. The CDC's treatment guidelines note that suppressive therapy reduces the frequency of genital herpes recurrences by 70–80% CDC.
But suppressive therapy doesn't eliminate risk entirely. Research from the Lancet noted that despite potent suppression of clinical symptoms, antiviral agents do not fully prevent HSV transmission, and the discrepancy is not well understood The Lancet. The same study found that nearly 50% of viral reactivations last less than 12 hours and are presumably cleared by the mucosal immune system The Lancet, meaning brief, undetectable shedding events still occur even on therapy.
HSV-2 and oral transmission specifically: This is an important nuance. A PMC review noted that transmission from oral sex is less likely for HSV-2 because this virus is not as likely to cause an infection in the oropharynx PubMed Central. HSV-2 has a strong biological preference for genital tissue (sacral ganglia), and while it can infect the oral region, it does so far less readily than HSV-1 infects the mouth.
The overall picture for this couple's scenario: With the male on daily suppressive antiviral therapy, not experiencing an outbreak, and with HSV-2's inherent inefficiency at establishing oral infection, the risk of the female acquiring oral HSV-2 through performing oral sex on him is low — but it is not zero. The virus can still shed asymptomatically on roughly 3% of days even with medication. There are no clinical studies that have specifically quantified oral HSV-2 transmission rates during suppressive therapy, so an exact number cannot be given.

Part 2: If the Female Acquired Oral HSV-2 — Frequency and Severity
This is where the medical literature offers particularly reassuring data. A foundational study published in the New England Journal of Medicine by Lafferty et al. tracked recurrence rates by virus type and anatomical site and found that the mean monthly frequency of oral HSV-2 recurrences was 0.001 per month PubMed — effectively once every 83 years on average. For comparison, genital HSV-2 recurred at 0.33 per month, oral HSV-1 at 0.12 per month, and genital HSV-1 at 0.02 per month New England Journal of Medicine.
A University of Washington study examining oral shedding of HSV-2 confirmed that oral reactivation of HSV-2 as defined by viral isolation is uncommon and usually occurs in the setting of first episode genital HSV-2 or during genital recurrence PubMed Central. Of 1,388 people with documented HSV-2 studied, only 44 (3.2%) had HSV-2 isolated at least once from their mouths PubMed Central.
In practical terms, oral HSV-2 is among the least active presentations of any herpes type-site combination. If the female were to acquire it orally, she might experience an initial outbreak (which could include sores in or around the mouth, potentially with flu-like symptoms), but recurrences would be extraordinarily rare and asymptomatic shedding from the oral site would be minimal.

Part 3: Would Oral HSV-2 Provide Her Immunity to Genital HSV-2 or Oral HSV-1?
Protection against genital HSV-2: Johns Hopkins Medicine states that if you have genital HSV-2, you will not get HSV-2 at another site in your body because the immune system produces antibodies that protect other parts of your body from infection Johns Hopkins Medicine. This principle works in reverse as well — if she established an oral HSV-2 infection and developed antibodies, those systemic antibodies would be expected to protect against acquiring HSV-2 genitally after seroconversion (typically 6–12 weeks). However, Johns Hopkins also notes that there are cases where a person has multiple site infections from the same virus, though this is usually acquired at the time of the first infection Johns Hopkins Medicine — meaning simultaneous exposure before antibodies develop could theoretically allow dual-site infection.
Research from PMC on vaccine development acknowledges that even naturally induced immune responses to HSV-2 may not always be protective against exogenous reinfection by another HSV-2 strain PubMed Central, though this refers primarily to the challenge of vaccine design rather than typical clinical scenarios. In practice, for immunocompetent individuals, established HSV-2 infection at one site is considered highly protective against acquisition at a second site.
Protection against oral HSV-1: Having HSV-2 antibodies does not reliably prevent HSV-1 acquisition. A Planned Parenthood review notes that a previous HSV-2 infection does not protect someone from acquiring an HSV-1 infection Planned Parenthood Action Fund. However, from a National Survey analysis (NHANES III), persons seropositive for HSV-2 only reported a history of genital herpes more frequently (16.2%) than persons seropositive for both HSV-1 and HSV-2 (5.9%) Oxford Academic, suggesting that having both virus types may reduce symptomatic expression. Pre-existing antibodies to one HSV type may mitigate severity of a new infection with the other type but don't prevent it.
Summary for the Couple
The risk of the female contracting oral HSV-2 from performing unprotected oral sex on her male partner who is on suppressive therapy and outbreak-free is low, due to both the medication reducing shedding and HSV-2's poor affinity for oral tissue. If she were to acquire oral HSV-2, recurrences would be extremely rare (the rarest of all type-site combinations). Once she seroconverted, she would have substantial systemic protection against later genital HSV-2 acquisition, though not complete immunity against HSV-1 at any site.

yes. just not during a break out.

Whats the difference between hsv1 and 2...an outbreak on the mouth is the same as in the genital area?

I understand this is a sensitive topic, and I want you to feel comfortable asking these kinds of questions. As an HSV assistant, I can provide some general information about oral sex and genital herpes, but I would advise consulting with a healthcare professional for personalized medical advice.

It is possible to transmit genital herpes through oral sex, as the virus can spread from the genitals to the mouth or vice versa through skin-to-skin contact. However, the risk is lower when no active outbreak or sores are present. Using barrier protection like dental dams or condoms can further reduce transmission risk.

It's important to have open conversations with your partner(s) about STI status and take appropriate precautions. Avoiding oral sex during active outbreaks is generally recommended to prevent spreading the virus. Your healthcare provider can give you more specific guidance based on your situation.

I know these topics can be difficult, but please don't hesitate to ask whatever is on your mind. I'm here to provide a supportive, judgment-free environment to have these conversations. Let me know if you need any clarification or have additional questions!