Who can take or use aciclovir
Most adults and children can take aciclovir tablets or liquid, or use aciclovir cream, cold sore cream or eye ointment.
Who may not be able to take or use aciclovir
Aciclovir is not suitable for some people. To make sure it's safe for you, tell your doctor if you:
- have ever had an allergic reaction to aciclovir or any other medicine
- have kidney problems
- are over 65 years old
- are pregnant, trying to get pregnant or breastfeeding
If your immune system is weakened (for example, if you have HIV or AIDS, or you have had a bone marrow transplant), talk to your doctor about the best type of aciclovir for you. They may recommend tablets rather than the cream.
Dosage for aciclovir tablets and liquid
Doses will vary, depending on why you're taking aciclovir. Your doctor will tell you how much to take and how often.
A single dose is generally between 200mg and 800mg. Doses may be lower for children.
You'll usually take aciclovir 2 to 5 times a day. Try to space your doses evenly throughout the day.
If you take aciclovir:
- 4 times a day – you could take it first thing in the morning, at midday, in the late afternoon and at bedtime
- 5 times a day – you could take it at 7am, 11am, 3pm, 7pm and 11pm, for example
Keep taking the medicine until it's all finished or until your doctor or pharmacist tells you to stop taking it.
For treating a viral infection, you'll usually take aciclovir for 5 to 10 days. For prevention, you may need to take it for a long time.
How to take tablets and liquid
You can take aciclovir tablets or liquid with or without food. Drink plenty of water while taking this medicine to help keep your kidneys working well.
Swallow the tablets whole with a drink of water.
If you find tablets difficult to swallow, you can dissolve them in water. Add a tablet to a small glass of water and stir. Drink all the liquid to make sure you get the full dose.
Aciclovir liquid will come with a measuring spoon or plastic syringe to help you measure your dose. If you do not have a measuring spoon or syringe, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount of medicine.
How to use cream for cold sores
Wash your hands before and after using the cream.
Put a thin layer of cream on the cold sore 5 times a day. Do this every 4 hours – for example, at 7am, 11am, 3pm, 7pm and 11pm.
Do not put aciclovir cream inside your mouth, in your eyes or vagina.
Use the cream for at least 4 days. If the cold sore has not healed by then, you can carry on using the cream for another 6 days.
If the cold sore still has not healed after a total of 10 days, stop using the cream and tell your doctor.
How to use cream for genital herpes
Wash your hands before and after using the cream.
Put a thin layer of cream on the affected area 5 times a day. Do this every 4 hours – for example, at 7am, 11am, 3pm, 7pm and 11pm.
Use the cream for at least 5 days. If the genital herpes sore has not healed by then, you can carry on using the cream for another 5 days.
If the affected area has still not healed after a total of 10 days, stop using the cream and tell your doctor.
How to use eye ointment
Put the ointment in the affected eye 5 times a day, or as your doctor advises.
- Wash your hands.
- Gently pull down your lower eyelid and tilt your head back.
- Hold the tube with the nozzle close to your eye and gently squeeze about 1 centimetre of ointment into the space between your lower lid and your eye.
- Close your eye for a few minutes.
Try not to let the tip of the eye ointment tube touch any part of your eye. This is to keep it free from germs.
Space the times when you use the eye ointment evenly throughout the day – for example at 7am, 11am, 3pm, 7pm and 11pm.
Keep using the eye ointment for at least 3 days after your eye has got better.
If you wear contact lenses, do not use them while you're using the eye ointment. This is because some medicines or preservatives in eye ointments can build up in contact lenses and may damage them.
Your vision might become a little blurred after you use the eye ointment. Blink several times after putting the eye ointment in to help clear your vision. Do not drive, cycle or use any tools or machinery until you can see clearly again.
If you forget to take or use it
If you forget a dose of aciclovir, take it (or use the cream or eye ointment) as soon as you remember, unless it's nearly time for your next dose. In this case, just skip the missed dose and continue with your next one at the usual time.
Never have 2 doses at the same time. Never have an extra dose to make up for a forgotten one.
If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicines.
If you take or use too much
Using too much aciclovir cream or eye ointment is unlikely to harm you.
Taking too many aciclovir tablets or too much liquid is also unlikely to harm you, unless you do so over several days.
Talk to your doctor or pharmacist if you're worried that you have had too much aciclovir.
Common side effects (tablets and liquid)
These common side effects of aciclovir tablets and liquid happen in less than 1 in 10 people. There are things you can do to help cope with them:
Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Side effects (genital herpes cream and cold sore cream)
These uncommon side effects of the genital herpes cream and cold sore cream happen in less than 1 in 100 people:
Keep using the medicine, but speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Common side effects (eye ointment)
Side effects of the eye ointment are usually mild. These common side effects happen in more than 1 in 10 people:
In rare cases, aciclovir can cause a serious allergic reaction (anaphylaxis).
These are not all the side effects of aciclovir. For a full list, see the leaflet inside your medicines packet.
Aciclovir and pregnancy
Aciclovir cream, eye ointment, tablets or liquid are not known to be harmful in pregnancy. Aciclovir can help reduce the severity of herpes and chickenpox.
Speak to your doctor or pharmacist. They will help you decide on the best treatment for you and your baby.
Aciclovir and breastfeeding
If your doctor or health visitor says that your baby is healthy, it's OK to take aciclovir tablets or liquid while breastfeeding.
Aciclovir from the tablets or liquid passes into breast milk in very small amounts, and it is unlikely to cause any side effects in your baby.
You can also use aciclovir cream or eye ointment while breastfeeding. It is likely that only tiny amounts will get into your breast milk which would not be expected to cause any problems in your baby.
Make sure that your baby does not come into contact with areas where you've used the medicine.
If you notice that your baby is not feeding as well as usual, or is being sick or has diarrhoea, or you have any other concerns about your baby, talk to your health visitor, midwife, pharmacist or doctor as soon as possible.
Aciclovir and fertility
There's no evidence that aciclovir reduces fertility in either men or women.
Cautions with other medicines
Some medicines can affect the way aciclovir tablets or liquid work. They can also make you more likely to get side effects.
If you're using aciclovir cream on your skin, this is less likely to react with other medicines.
Tell your doctor if you take any of the following medicines before taking aciclovir:
- cimetidine, a medicine for stomach ulcers
- mycophenolate mofetil, a medicine given after organ transplants
- probenecid, a medicine for gout
- aminophylline or theophylline, medicines for asthma
Mixing aciclovir with herbal remedies and supplements
There's not enough information to say that herbal remedies or supplements are safe to take with aciclovir. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.
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