Genital Herpes: The Antiviral Doses, the Real Transmission Numbers and What the Blood Test Means

Most of the distress caused by a genital herpes diagnosis comes from not knowing four numbers: how often it is likely to come back, how often the virus is present without symptoms, how much treatment reduces the risk to a partner, and what the blood test actually proves. This page is those four numbers and the doses that go with them.

The first one is the most useful, and it depends on which virus you have.

🧬 Two viruses, two very different outlooks

Herpes simplex comes in two types, and knowing yours changes the prognosis considerably. Increasingly, genital infection is caused by HSV-1 passed on through oral contact rather than by HSV-2.

Which is why asking which type you have is worth doing. A new diagnosis of genital HSV-1 in someone expecting a lifetime of monthly outbreaks is a much better piece of news than most people are given.

🧪 Testing: what each test actually proves

• 🧫 A swab of a fresh lesion, tested by PCR — the best test. It confirms herpes, and it says which type, which is the information above. Taken from a new blister or ulcer rather than a crusted one
• 🩸 Type-specific IgG blood test — shows past infection with HSV-1 or HSV-2. Useful when there are no lesions to swab, or to clarify a partner situation. It cannot say where on the body the infection is
• 🚫 IgM testing should not be used. It does not reliably distinguish new from old infection, it cross-reacts between types, and it produces false positives. If a laboratory reports an HSV IgM result, it is not a basis for a diagnosis

And because the appearance varies so much — classic blisters in some people, a small fissure, a patch of soreness or something resembling a shaving rash in others — an uncertain diagnosis is worth confirming with a swab rather than accepted on sight. Several conditions mimic it closely.

💊 The doses, by situation

This is the part the subject actually turns on. The three drugs are equivalent in effect; they differ in how many tablets a day and in price. Valtrex (Valacyclovir) is usually chosen for the simplest schedule.

The alternatives are Zovirax (Acyclovir), the original and the cheapest, and Famvir (Famciclovir), which has the shortest recurrence course at a single day. All three sit in the antiviral category.

• 💧 Drink normally and keep hydrated while taking any of them
• 🫀 All three need the dose reduced if kidney function is reduced, so mention any kidney problem. This is the main safety consideration and it is easily handled
• 🤢 Side effects are usually mild — headache and nausea being the common ones
• 💊 Suppressive therapy is reviewed roughly yearly, because recurrence frequency falls over time and many people can stop

📉 Transmission, with the actual figures

The honest picture, which is more reassuring than the vagueness usually offered and also less absolute.

Two facts belong alongside those. Transmission can occur without any symptoms, because the virus is shed from normal-looking skin on a meaningful proportion of days — this is why avoiding contact during outbreaks alone is not a complete strategy. And risk is highest in the first year after infection, when both recurrences and shedding are most frequent, then falls.

In a couple where one partner is infected and the other is not, it is worth both being tested, because a surprising number of partners turn out to already carry the same virus, which changes the conversation entirely.

🤰 Pregnancy: the part that genuinely matters

Neonatal herpes is rare and it is serious, and the risk depends almost entirely on when the mother was infected rather than on whether she has herpes at all.

• 📣 Tell the maternity team you have genital herpes, at booking, even if you have had no outbreak for years. The plan depends on it
• 🚫 A woman who has never had herpes and whose partner has it should avoid unprotected contact in the third trimester entirely, and avoid receiving oral sex from a partner with cold sores. Acquiring it late in pregnancy is the dangerous scenario
• ✅ Acyclovir is considered safe in pregnancy and is the one with the longest record
• 👶 Newborns: any blistering rash, fever, poor feeding, floppiness or unusual irritability in a baby in the first weeks needs immediate assessment

🚨 Complications and the ones that need urgent care

• 🚽 Inability to pass urine — severe first episodes can cause this through pain and nerve involvement, and it sometimes needs catheterisation. Do not wait it out
• 🧠 Severe headache with neck stiffness, light sensitivity or vomiting during a first episode — herpes can cause an aseptic meningitis, which usually resolves and needs assessing
• 👁️ Eye pain, redness or blurred vision — herpes affecting the eye is sight-threatening and needs same-day ophthalmology, not a wait
• 👆 A painful swollen fingertip with blisters — herpetic whitlow, from touching lesions. Which is also why hand washing after any contact with the area matters
• 🌡️ Widespread blistering in someone with eczema — eczema herpeticum, a medical emergency
• 🛡️ Immunosuppression — HIV, chemotherapy, transplant medication, high-dose steroids. Outbreaks are longer, more severe, more frequent and need higher doses and specialist input
• 📈 Lesions not healing on treatment — raises the question of resistance or of another diagnosis entirely, and needs reassessment rather than a repeat course

🩸 What else to be tested for

A new diagnosis of genital herpes is a reason for a full sexual health screen, and one connection is worth stating plainly.

Genital herpes increases the risk of acquiring HIV roughly threefold, because the breaks in the skin and the immune cells drawn to them provide an easier route in. That makes an HIV test part of the workup rather than an afterthought, along with chlamydia, gonorrhoea and syphilis. If another infection is present, it is better found now.

Genital lesions have several other causes worth excluding, and one of them — genital warts from HPV — is covered in our guide to external genital warts. The related condition shingles, caused by a different member of the same virus family, is covered in our guide to shingles and the 72-hour window, and general background on the drug itself is in our note on treating herpes with valacyclovir.

🧴 Getting through an outbreak

The antiviral handles the virus. These handle the week.

• 🚿 Warm salt water baths, or pouring warm water over the area while passing urine, which removes most of the stinging
• 💊 Paracetamol or an anti-inflammatory for pain, and a topical local anaesthetic gel for severe cases
• 🧺 Loose cotton underwear, and nothing tight or synthetic while lesions are present
• 🧴 Leave the skin alone. Over-washing, antiseptics, scrubbing and repeatedly checking the area all prolong healing. Gentle cleansing and drying is the whole routine
• 🧼 Wash hands after any contact with the area, and do not touch your eyes
• 🚫 No sexual contact until lesions have fully healed

On triggers: outbreaks cluster around physical stress, poor sleep, other illnesses, friction and sometimes the menstrual cycle. Friction is the most actionable of those — aggressive shaving or waxing, and prolonged or dry friction, provoke recurrences in a lot of people, and lubrication and leaving the skin alone during sensitive periods prevent more outbreaks than any supplement.

💬 Telling a partner

The conversation is almost always worse in anticipation than in practice. What helps is having the numbers rather than only the diagnosis, because the first question is going to be about risk.

Something short works better than a speech: I have genital herpes. It is very common, I do not currently have symptoms, and there are specific things that lower the risk a lot — daily antiviral treatment roughly halves it, condoms help, and we avoid contact if I get warning signs. Ask me anything and we can see a clinician together if you want.

Two things worth knowing. A large share of people with HSV-2 do not know they have it, so a partner may already be infected —> testing both of you is reasonable. And the diagnosis is far commoner than the silence around it suggests, which is worth remembering when it feels isolating.

🚫 Four things that are not true

📞 When to seek help

Urgent:

• Unable to pass urine
• Severe headache with neck stiffness, light sensitivity or vomiting
• Eye pain, redness or visual change
• Widespread blistering, particularly with eczema
• A newborn with a blistering rash, fever, poor feeding or floppiness
• A first-ever outbreak in late pregnancy

Promptly:

• A first episode — antiviral treatment started early shortens it considerably, and swabbing confirms the type
• Any genital sore or ulcer you have not had before, for a swab and a full sexual health screen
• Not knowing which type you have — ask, because the prognosis differs
• Six or more recurrences a year, or outbreaks disrupting work or relationships — suppressive therapy is appropriate
• An uninfected partner, where suppressive therapy is a specific option worth discussing
• Pregnancy, or planning it
• No home supply for early treatment, if outbreaks recur — ask for one
• Lesions not healing on treatment
• Immunosuppression of any kind
• Persistent low mood or anxiety about the diagnosis, which is common, under-acknowledged and treatable

❓ Frequently asked questions

📑 Sources and editorial

• CDC sexually transmitted infections treatment guidelines and international guidance on the management of genital herpes, including episodic and suppressive dosing
• Guidance on herpes simplex serological testing, including type-specific IgG interpretation, the limitations of IgM assays, and recommendations against screening asymptomatic people
• Natural history studies of genital HSV-1 and HSV-2 recurrence frequency and the decline in recurrence rate over time
• Studies of asymptomatic viral shedding measured by PCR, by virus type and by time since infection
• The randomised trial of once-daily valacyclovir for reducing transmission of genital herpes between discordant partners, and studies of condom effectiveness in HSV-2 transmission
• Prescribing information for valacyclovir, acyclovir and famciclovir, including renal dose adjustment
• Obstetric guidance on genital herpes in pregnancy, covering neonatal transmission risk by timing of maternal infection, suppressive therapy from 36 weeks and mode of delivery
• Reviews of HSV complications including urinary retention, aseptic meningitis, herpetic whitlow, ocular disease and eczema herpeticum
• Epidemiological studies of HSV-2 infection and HIV acquisition risk
• Related reading: treating herpes with valacyclovir, shingles and the 72-hour window, external genital warts
• Related products: Valtrex (Valacyclovir), Zovirax (Acyclovir), Famvir (Famciclovir), antiviral category
• RXshop Editorial Team — reviewed by Emily Chen, MD, MPH — Internal Medicine Specialist