Herpes simplex virus type 2 (HSV-2): genital herpes explained

Genital herpes is a sexually transmitted infection passed on through vaginal, anal and oral sex, caused by herpes simplex virus. NICE CKS explains that the virus becomes latent in nearby sensory nerve cells after the first infection and can reactivate, causing either visible sores or infectious shedding of virus without symptoms.

The NHS notes that once you have the virus it stays in your body, does not spread through the body to cause blisters elsewhere, and causes blisters in the same area from a nearby nerve.

The NHS lists small blisters that burst to leave red, open sores around the genitals, anus, thighs or bottom (which may be less red on brown or black skin), tingling, burning or itching around the genitals, pain when you pee, and unusual discharge. NICE CKS adds that recurrent episodes are typically milder, one-sided and more localised than the first, and often preceded by tingling or pain in the genital area, back, buttocks or thighs up to 48 hours earlier.

The NHS recommends going to a sexual health clinic as soon as possible with symptoms, even if you have not had sex for a long time, because blisters can take months or years to appear. A GP can see you but will probably refer you to a clinic. Many clinics offer walk-in services, often get test results quicker than GP practices, and do not charge a prescription fee.

The doctor or nurse asks about symptoms and sexual partners and takes fluid from a blister or sore using a small cotton swab. The NHS says the test cannot be done if you have no visible blisters or sores, and cannot tell you how long you have had herpes or who you got it from.

For a first episode the NHS says you may be prescribed antiviral medicine to stop symptoms getting worse, which must be started within 5 days of symptoms appearing, and a cream for pain. If symptoms began more than 5 days earlier you can still be tested to find the cause.

For later outbreaks the NHS says antiviral medicine may shorten an outbreak by 1 or 2 days if you start it as soon as symptoms appear, but outbreaks usually settle by themselves so you may not need treatment. Recurrences are usually milder, and over time outbreaks tend to happen less often and be less severe. Some people who have more than 6 outbreaks in a year may benefit from taking antiviral medicine for 6 to 12 months, and a specialist referral is possible if outbreaks continue on that treatment.

• Keep the area clean with plain or salt water.

• Use an ice pack wrapped in a flannel, never ice directly on skin.

• Petroleum jelly or 5% lidocaine cream can reduce pain when you pee, and passing urine while pouring water over the genitals can ease the sting.

• Wear loose clothing and avoid sex until the sores have gone.

The NHS says genital herpes is very easy to pass on from the first tingling or itching of a new outbreak until sores have fully healed, and you may be able to pass it on without symptoms. The risk is higher in the first 6 months of infection and rare after 2 years. It spreads by skin-to-skin contact, including when there are no visible sores, from a cold sore touching the genitals, on fingers, and through shared sex toys. You cannot get it from towels, swimming pools, saunas or toilet seats.

Condoms help, though herpes can still pass on if the condom does not cover the infected area. Avoiding sex when you or your partner has sores or a tingle or itch that signals an outbreak is advised. NICE CKS also mentions episodic and suppressive antiviral options as part of recurrence management.

Women who had genital herpes before pregnancy can usually expect a healthy baby and a vaginal delivery, says the NHS. The concern is neonatal herpes, a serious illness that can be fatal although most babies recover with treatment. Risk is low if you have had genital herpes before and higher if you first get it in the last 6 weeks of pregnancy. Antiviral treatment may be offered from week 32 to reduce the chance of an outbreak at birth, or from diagnosis until birth if herpes is first acquired after week 28. See your midwife or GP if you think you have genital herpes in pregnancy.

For people with HIV or a weakened immune system, the NHS says genital herpes can be more serious, and a genitourinary medicine specialist is involved.