Aciclovir 400mg tablets - genital herpes outbreaks

Aciclovir is an antiviral medicine. It’s switched on only inside cells that the herpes virus has infected, where it stops the virus copying its DNA. That helps an outbreak heal faster and reduces pain, and because healthy cells largely ignore it, it’s generally well tolerated.

No. After the first infection, the herpes virus stays in the nerves, where no medicine can reach it, and can reactivate from time to time. Aciclovir treats outbreaks but doesn’t remove the virus. The good news is that outbreaks usually become milder and less frequent over the years, and herpes doesn’t harm your general health.

As early as possible, ideally at the first tingle, itch or burning, before blisters appear. Aciclovir stops the virus copying itself, and most copying happens early in an outbreak. Starting later still helps, but less. That’s why many people keep a pack at home.

This pack is 400mg tablets: one tablet three times a day for 5 days, to treat one outbreak. This is the course recommended in UK sexual health guidance (BASHH). Always follow the instructions from your prescriber, who will check your kidney health and other medicines first.

Pain and tingling often start to ease within a day or two. Sores take longer to crust over and heal. A recurrent outbreak often settles within a week or so anyway; starting aciclovir early can shorten it by a day or two and make it less painful.

Aciclovir is usually well tolerated. Up to 1 in 10 people get a headache, dizziness, feeling sick, diarrhoea, tummy pain, itching or a rash. Very rarely, it can affect the kidneys or cause confusion, mainly in older people and people with kidney problems. Drinking plenty of fluids during the course helps. Get medical help for a rash with swelling, or if you pee much less than usual.

A short course treats your outbreak, but it doesn’t stop you passing herpes on. Avoid sex, including oral sex, from the first tingle until the sores have completely healed, use condoms between outbreaks, and tell partners. Daily antiviral treatment from your GP or a sexual health clinic roughly halves the risk of passing on HSV-2, but doesn’t remove it.

Daily (suppressive) treatment can prevent most outbreaks and is usually considered if you have 6 or more a year, or very troublesome ones. It’s reviewed after a year. Our online service supplies treatment for individual outbreaks only, so please ask your GP or a sexual health clinic about daily treatment.

Not through our online service. Herpes in pregnancy needs to be managed by your maternity team, who may offer antiviral treatment in the last weeks of pregnancy to reduce the risk to your baby. Tell your midwife if you or your partner have ever had genital herpes. If you’re breastfeeding, please see your GP, as aciclovir passes into breast milk.

There are only a few important interactions. Probenecid and cimetidine can raise aciclovir levels, and mycophenolate, ciclosporin, tacrolimus and theophylline may need extra checks. Take care with medicines that can affect the kidneys, such as regular high-dose anti-inflammatory painkillers. Tell the prescriber everything you take, including medicines bought over the counter.

Take it as soon as you remember, unless it’s nearly time for the next dose. In that case skip the missed dose and carry on as normal. Never take two doses at once. Missing one dose of a short course is unlikely to stop it working.

They work equally well for treating outbreaks. Valtrex (valaciclovir) is turned into aciclovir in the body and absorbed better, so it’s taken twice a day instead of three times. Aciclovir costs less. The prescriber will help you decide. Our aciclovir vs valaciclovir guide compares them.