How does aciclovir work?
Aciclovir stops the herpes virus growing and spreading.
This controls the infection and helps your body's immune system deal with it.
No medicine or treatment will remove the herpes virus from your body completely.
When will I feel better?
You should start to feel better after taking or using aciclovir for a few days.
What can I do if the treatment is not working?
Tablets and liquid
If you're not feeling better after you finish your prescribed course of aciclovir, tell your doctor.
If your symptoms get worse at any time during your treatment, speak to your doctor.
They may want to increase your dose of aciclovir.
Cream for genital herpes
If your genital herpes sore is not better after 5 days, you can use the cream for another 5 days.
If the infection gets worse at any time or the sore still has not healed after 10 days, speak to your doctor.
Cold sore cream
If your cold sore has not healed after 4 days, you can carry on using the cold sore cream for another 6 days.
If your cold sore still has not healed after this or it gets worse at any time, stop using the cream and speak to your doctor.
Eye ointment
If your eye infection is not better by the end of the course, or if it gets worse during your treatment, speak to your doctor. You may need to take aciclovir tablets or a different medicine if your eye infection is severe or keeps coming back.
Can I have sex while I'm taking aciclovir?
If you have been prescribed aciclovir for genital herpes, do not have sex until all your sores or blisters have healed.
It's important to always use a condom when having sex, even after your symptoms have gone.
If you or your partner have cold sores, avoid kissing and oral sex until the sores have healed.
This reduces the risk of passing the infection on to your partner.
Will aciclovir affect my contraception?
Aciclovir will not stop any type of contraception from working, including the combined pill, progestogen-only pill and emergency contraception.
However, if aciclovir makes you sick (vomit) or have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.
Find out more:
Can I drive or ride a bike?
Some people feel dizzy when taking aciclovir tablets or liquid. This may make it more difficult to concentrate and react.
You may not be able to see clearly for 5 to 10 minutes after using the eye ointment.
Do not drive, cycle or use any tools or machines if you're affected.
It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.
Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking aciclovir. GOV.UK has more information on the law on drugs and driving.
Can I drink alcohol while taking aciclovir?
Yes, you can drink alcohol while taking aciclovir.
Is there any food or drink I need to avoid?
You can eat and drink normally while taking aciclovir.
Can lifestyle changes prevent cold sores or herpes infections?
Try to avoid or manage the things that trigger the herpes virus.
These include:
- stress – try to reduce physical and emotional stress
- being overtired – make sure you get enough sleep and eat a healthy, balanced diet
- strong sunlight and ultraviolet light – use a lip balm with SPF 30 or higher and avoid using sunbeds
To avoid passing the infection on, do not kiss anyone while you have a cold sore. If you have genital herpes, do not have sex until the sores have gone away.