A cold sore and genital herpes are caused by the same kind of virus. HSV-1 classically sits around the mouth, HSV-2 classically around the genitals. That split has blurred over the past twenty years, and it changes how you should read a result.
I think this is the most underrated piece of knowledge about herpes. Without the type distinction a positive result is almost impossible to place, and people end up worrying for no reason.
We put the two types side by side. For the complete picture, read our overview of genital herpes.
What is the difference between HSV-1 and HSV-2?
They are two related viruses that behave the same way: they cause blisters, then withdraw into a nerve root, and can become active again later. The difference lies in where they usually sit, how often they come back, and how common they are.
HSV-1 is by far the more widespread. In 2012 an estimated 3.7 billion people under 50 carried it worldwide, roughly 67 percent of that age group (Looker et al., 2015). Most of them do not know it, because a cold sore is the only visible sign.
| HSV-1 | HSV-2 | |
|---|---|---|
| Classic location | Lip and mouth | Genitals and anus |
| Genital too? | Yes, increasingly | Rarely oral |
| How common | Very common | Less common |
| Genital recurrences | Usually fewer | More often recurring |
| Our test | HSV-1 IgG | HSV-2 IgG |
That last row is exactly why a herpes test has to be type-specific. A result that only says you have herpes is barely usable.
Can a cold sore give you genital herpes?
Yes, it can. During oral sex, HSV-1 can travel from the mouth to the genitals. That is the very route that undermined the old split between the two types. It mostly happens when someone has an active cold sore, but transmission is possible without a visible one too.
Worldwide, an estimated 140 million people aged 15 to 49 had a genital HSV-1 infection in 2012 (Looker et al., 2015). That is no longer a fringe phenomenon.
Among young women, HSV-1 has even become the most common cause of a first herpes infection, at 2.5 new cases per 100 person-years against 1.1 for HSV-2 (Bernstein et al., 2013).
Which type causes more outbreaks?
Genital HSV-2 comes back more often on average than genital HSV-1. That is the practical difference that matters most to you. A genital HSV-1 infection often causes few or no recurring symptoms after the first period, while HSV-2 tends to show up again.
Picture two people who both get genital herpes after 1 risk moment: one turns out to have HSV-1, the other HSV-2. A year on, the first may have noticed nothing more, and the second a handful of episodes.
You see the same pattern in how often the virus is present without symptoms. With HSV-2, the virus was still found on 10.2 percent of days in people without symptoms (Tronstein et al., 2011). More on that in how you get herpes.
How do you know which type you have?
Only with a type-specific test. A PCR on a blister can name the type, and a blood test measures HSV-1 IgG and HSV-2 IgG separately. Without that split you only know you once caught herpes, and that is too little to act on.
With us you can test HSV-1 IgG and HSV-2 IgG separately and add them to your own test. They are not in the standard STI packages, because RIVM and Dutch STI practice do not screen for herpes routinely.
Which test fits which situation is covered in herpes test.
What does the type mean for your partner?
The type mostly decides how big the chance is that you pass it on, and where. Genital HSV-2 stays more active, so the conversation about condoms and outbreaks matters more there. An old HSV-1 cold sore is a non-issue for most couples.
Still, it is a conversation worth having. Thuisarts.nl writes about this in plain language, and our own experience is that people fear the conversation more than the virus.
Want to test together with your partner before you stop using condoms? Then testing together in a new relationship is a good starting point. Seeing something now and unsure what it is? Start at bumps or blisters on your genitals.
Sources
- Looker KJ, Magaret AS, May MT, et al. Global and regional estimates of prevalent and incident herpes simplex virus type 1 infections in 2012. PLoS One. 2015;10(10):e0140765. PMID 26510007.
- Bernstein DI, Bellamy AR, Hook EW, et al. Epidemiology, clinical presentation, and antibody response to primary infection with herpes simplex virus type 1 and type 2 in young women. Clin Infect Dis. 2013;56(3):344-351. PMID 23087395.
- Tronstein E, Johnston C, Huang ML, et al. Genital shedding of herpes simplex virus among symptomatic and asymptomatic persons with HSV-2 infection. JAMA. 2011;305(14):1441-1449. PMID 21486977.
- RIVM. STI guidelines and sexual health surveillance. Available via rivm.nl.
- Thuisarts.nl (NHG). I have a cold sore. Available via thuisarts.nl.
This information is general and does not replace personal medical advice. Every STI test result at Discreet Test is reviewed by a BIG-registered doctor. Always discuss symptoms or treatment decisions with your GP, the GGD or a Centre for Sexual Health.
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