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Aciclovir

About aciclovir

Aciclovir (or acyclovir) is an antiviral medicine.

It treats infections caused by the herpes virus (herpes simplex), including:

  • cold sores
  • genital herpes

Your doctor may prescribe aciclovir to prevent you getting these infections if you have had them before or you have a weak immune system.

It's also used to treat chickenpox and shingles.

Aciclovir is available on prescription. It comes as tablets, a liquid that you drink and a cream.

It's sometimes given by injection, but this is usually only done in hospital.

You can buy aciclovir cold sore cream at most pharmacies and supermarkets without a prescription.

Key facts

  • Start taking aciclovir as soon as you get the first signs of infection.
  • For most infections, you should start to feel better after taking aciclovir for a few days.
  • Common side effects include headaches, dizziness, and feeling or being sick.
  • Wash your hands before and after using the cream.
  • Brand names include Zovirax, Cymex Ultra and Virasorb.

Who can and cannot take aciclovir

Aciclovir can be taken by most adults and children.

Aciclovir is not suitable for some people.

To make sure aciclovir is safe for you, tell your doctor if you:

  • have had an allergic reaction to aciclovir or any other medicine in the past
  • 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.

How and when to take it

It's important to start taking (or using) this medicine as soon as you get the first signs of infection.

A cold sore usually starts with a tingling, itching or burning feeling.

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, and may be lower for children.

You'll usually take aciclovir 2 to 5 times a day. Try to space the 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 – for example, you could take it at 7am, 11am, 3pm, 7pm and 11pm

You can take aciclovir with or without food. Drink plenty of water while taking this medicine to help keep your kidneys working well.

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.

Tablets: swallow the tablets whole with some 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.

Liquid: use the measuring spoon or plastic syringe that came with your medicine. If you do not have a measuring spoon or syringe, ask your pharmacist for one. Do not use a kitchen teaspoon as you will not get the right amount of medicine.

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 in your mouth, 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 sore still has not healed after a total of 10 days, stop using the cream and tell your doctor.

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.

What if I forget a dose of aciclovir?

If you forget a dose of aciclovir, take it (or use the cream) 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 as normal.

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 remember your medicines.

What if I take or use too much?

Taking too much aciclovir by accident is unlikely to harm you, unless you take too much over several days.

Talk to your doctor or pharmacist if you're worried that you have had too much aciclovir.

Side effects

Like all medicines, aciclovir can cause side effects in some people, although not everyone gets them.

Many people have no side effects at all, or only minor ones.

Common side effects (tablets and liquid)

These common side effects happen in more than 1 in 10 people who take aciclovir tablets or liquid.

Keep taking the medicine, but talk to your doctor or pharmacist, if these side effects bother you or do not go away:

  • headaches
  • feeling dizzy
  • feeling or being sick (nausea or vomiting)
  • diarrhoea
  • skin being sensitive to sunlight

Common side effects (cream)

The cold sore cream is generally very safe and less than 1 in 100 people experience any side effects.

Keep using the medicine, but talk to your doctor or pharmacist, if these uncommon side effects bother you or do not go away:

  • burning or stinging for a short time after applying the cream
  • itchy, dry or flaky skin

Serious allergic reaction

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.

How to cope with side effects

What to do about:

  • headaches – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Paracetamol is safe to take with aciclovir if you need a painkiller. Speak to your doctor if this does not help or your headaches are severe.
  • feeling dizzy – if aciclovir makes you feel dizzy, stop what you're doing and sit or lie down until you feel better. Do not drive, ride a bike, or use tools or machinery if you feel dizzy.
  • feeling or being sick (nausea or vomiting) – stick to simple meals and do not eat rich or spicy food. It might help to take your medicine after you have eaten. If you're being sick, try small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
  • diarrhoea – drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
  • skin being sensitive to sunlight – stay out of bright sun and use a high factor sun cream (SPF 15 or above) even on cloudy days. Do not use a sun lamp or sun beds.
  • burning or stinging feeling after applying the cream – this usually goes away after a short time. Ask a pharmacist or your doctor for advice if it continues to be a problem.
  • itchy, dry or flaking skin – try using an unscented moisturiser. Do not apply the moisturiser at the same time as your aciclovir cream.

Pregnancy and breastfeeding

It's usually safe to use the cream or take aciclovir during pregnancy.

Speak to your doctor, who'll be able to explain the benefits and the risks of taking aciclovir when pregnant.

They can help you decide on the best treatment for you and your baby.

For more information about how aciclovir can affect you and your baby during pregnancy, read this leaflet on the best use of medicines in pregnancy (bumps) website.

Aciclovir and breastfeeding

It's usually safe to breastfeed while taking aciclovir.

If you're taking the tablets or liquid, some of the medicine passes into your breast milk.

This is in small amounts and is unlikely to harm your baby.

Talk to your doctor if you want to breastfeed while taking aciclovir. They can advise you on what's best for you and your baby.

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.

It's important to 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 very little information about taking herbal remedies and supplements while taking or using aciclovir.

Common questions

HealthUnlocked contains information from NHS Digital, licensed under the current version of the Open Government Licence

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153 public posts

Shingles!

I happened to have an appointment with my consultant and she decided to prescribe a prophylactic dose of Aciclovir, as I'm on Ruxolitinib, therefore immune suppressed. A couple of days later actual Shingles developed and I am now just starting 5 x 800mg of Aciclovir a day.
I happened to have an appointment with my consultant and she decided to prescribe a prophylactic dose of Aciclovir, as I'm on Ruxolitinib, therefore immune suppressed. A couple of days later actual Shingles developed and I am now just starting 5 x 800mg of Aciclovir a day.
Otterfield
in MPN Voice

Waning PMR now shingles. New poster.

Put on 800 mg aciclovir X 5 per day. Not so pleased now. Is shingles common within the PMR club members?
Put on 800 mg aciclovir X 5 per day. Not so pleased now. Is shingles common within the PMR club members?
Pesterfootbridge
in PMRGCAuk

Varicella zoster encephalitis

He is taking Aciclovir. I'd like to know please, what will the health outcomes be? He has not gone into coma and seems to be recovering, though very slowly. He is awake but not lucid, his speech is still confused. Does he have a fair chance of surviving?
He is taking Aciclovir. I'd like to know please, what will the health outcomes be? He has not gone into coma and seems to be recovering, though very slowly. He is awake but not lucid, his speech is still confused. Does he have a fair chance of surviving?
reluinta
in Encephalitis Society
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Shingles

Doctor prescribed a course of aciclovir. Pain unbearable so now been put on pregabalin which at first seem ok. Worried that I could be the 1 in 4 that gets PHN.. Anybody suffered with this...
Doctor prescribed a course of aciclovir. Pain unbearable so now been put on pregabalin which at first seem ok. Worried that I could be the 1 in 4 that gets PHN.. Anybody suffered with this...
Blueboy1946
in Pain Concern

Shingles - part 3

The GP was actually quite panicky, he told me to come down immediately and pick up Aciclovir, he said that 5 spots is probably just the start and it must be nipped in the bud and worse still I am to stop taking the methotrexate. Great!
The GP was actually quite panicky, he told me to come down immediately and pick up Aciclovir, he said that 5 spots is probably just the start and it must be nipped in the bud and worse still I am to stop taking the methotrexate. Great!
Brychni
in NRAS

Starting Acalabrutinib

Also, there are other drugs that I'm supposed to take too - Aciclovir, Allopurinol, Co-TrimOxazole. What puzzles me is, if there are any side-effects, how to the docs know which drug is causing them?
Also, there are other drugs that I'm supposed to take too - Aciclovir, Allopurinol, Co-TrimOxazole. What puzzles me is, if there are any side-effects, how to the docs know which drug is causing them?
bmredsea
in Positive Wellbeing During Self-Isolation

Shingles and vaccinations

(Whilst on Tocilizumab, I have had a mild Shingles outbreak, but knowing what to look for, I immediately got my GP to prescribe Aciclovir which cleared it up in 8 days). I have a dear friend who had really dreadful Shingles more than 3 years ago.
(Whilst on Tocilizumab, I have had a mild Shingles outbreak, but knowing what to look for, I immediately got my GP to prescribe Aciclovir which cleared it up in 8 days). I have a dear friend who had really dreadful Shingles more than 3 years ago.
Suzita76
in PMRGCAuk

Aciclovir 800mg

Recently been taking aciclovir 800mg tablets to help with my shingles . Have it on the back of my torso and after 3 days of medication the back of my head starting to itch? Any help???
Recently been taking aciclovir 800mg tablets to help with my shingles . Have it on the back of my torso and after 3 days of medication the back of my head starting to itch? Any help???
ra18722
in Kidney Disease

CLL & the Corona virus

I have been on the FLAIR drug trials for five years, taking Ibrutinib, plus Co-Trimoxazole and Aciclovir. My blood cancer has gone into remission, but there are still enough bad cells for me to continue on the drugs. Recently I developed a dry cough and inflamed vocal cords.
I have been on the FLAIR drug trials for five years, taking Ibrutinib, plus Co-Trimoxazole and Aciclovir. My blood cancer has gone into remission, but there are still enough bad cells for me to continue on the drugs. Recently I developed a dry cough and inflamed vocal cords.
hazelmark
in CLL Support

herpes vacine

Can I take the. herpes zoster vaccine in view I have LLC I am now suffering one and taking 400mg acyclovir 5 ties a day. Its painful and my stomach is bdestroyed
Can I take the. herpes zoster vaccine in view I have LLC I am now suffering one and taking 400mg acyclovir 5 ties a day. Its painful and my stomach is bdestroyed
giuliano
in CLL Support

Help deciding about Transplant

I was diagnosed with Primary MF aged 49, 6 years ago. I am well managed on Ruxolitinib 30 mg daily, Aspirin and Acyclovir. My consuhas recently referred me to a transplant construct discuss a possible transplant. I am trying make my decision, which I am finding so difficult. As I am well controlled
I was diagnosed with Primary MF aged 49, 6 years ago. I am well managed on Ruxolitinib 30 mg daily, Aspirin and Acyclovir. My consuhas recently referred me to a transplant construct discuss a possible transplant. I am trying make my decision, which I am finding so difficult. As I am well controlled
Cazbolac
in MPN Voice

Is it arthritis? Is it COVID19? Is it shingles? Can I run?

Ok, I haven't been able to run for a while. It started with some pain in my knees and hip, after that I tried again and when I was about to run for the 3rd time I caught a cold, very tired for 3 days, a weird sensitivity under the armpits and a dry wheezy cough. On Thursday I had the COVID test and
Ok, I haven't been able to run for a while. It started with some pain in my knees and hip, after that I tried again and when I was about to run for the 3rd time I caught a cold, very tired for 3 days, a weird sensitivity under the armpits and a dry wheezy cough. On Thursday I had the COVID test and
StarkeyGoGraduate
in Couch to 5K

U.K Herpes treatment specialist. MHRA approved blood test. HSV2 Herpes of Sinus

Please help!. I am 99.9% sure i have HSV2 (Genital Herpes) of septum/sinus, airway, throat etc, yet can not access reliable test to prove it. I am becoming depressed and desperate. Microbiology rejected my G.P request for antibody test (wasted my blood taken/sent). Only test i am offered is swab test
Please help!. I am 99.9% sure i have HSV2 (Genital Herpes) of septum/sinus, airway, throat etc, yet can not access reliable test to prove it. I am becoming depressed and desperate. Microbiology rejected my G.P request for antibody test (wasted my blood taken/sent). Only test i am offered is swab test
Theresa7
in Sexual Health Matters

Reliable U.K HSV2 blood test MHRA ?!

Please help!. I am 99.9% sure i have HSV2 (Genital Herpes) of septum/sinus, airway, throat etc, yet can not access reliable test to prove it. I am becoming depressed and desperate. Microbiology rejected my G.P request for antibody test (wasted my blood taken/sent). Only test i am offered is swab test
Please help!. I am 99.9% sure i have HSV2 (Genital Herpes) of septum/sinus, airway, throat etc, yet can not access reliable test to prove it. I am becoming depressed and desperate. Microbiology rejected my G.P request for antibody test (wasted my blood taken/sent). Only test i am offered is swab test
Theresa7
in BASHH

Hello! My father is a CKD patient and unfortunately just had Herpes(eyelid & scalp). Acyclovir was prescribed. Is it safe for him?

The dermatologist prescribed the meds and asked to further check with the Nephrologist. However, if my dad only uses the cream, would it work?
The dermatologist prescribed the meds and asked to further check with the Nephrologist. However, if my dad only uses the cream, would it work?
PEARL2478
in Kidney Transplant Patient Support

Neck pain?

I am a PMR sufferer who weaned off Prednisone 3 weeks ago, after a slow march down from 40 mg. Two weeks ago I awoke with left-sided facial paralysis, diagnosed as unrelated Bell’s palsy. It’s not serious, and goes away in a few months for 85% of its victims. Treatment is high dose Acyclovir (anti-viral
I am a PMR sufferer who weaned off Prednisone 3 weeks ago, after a slow march down from 40 mg. Two weeks ago I awoke with left-sided facial paralysis, diagnosed as unrelated Bell’s palsy. It’s not serious, and goes away in a few months for 85% of its victims. Treatment is high dose Acyclovir (anti-viral
RiverKings
in PMRGCAuk

Can taking Bactrim make you neutropenic?

My husband has been on Ibrutinib for 2 years now, and has taking Bactrim and Acyclovir along with it. Up until four months ago, his numbers have been in the more normal range. He feels well, and had a good CT scan in June. But in the last month his WBC, neutrophils and platelets have fallen drastically
My husband has been on Ibrutinib for 2 years now, and has taking Bactrim and Acyclovir along with it. Up until four months ago, his numbers have been in the more normal range. He feels well, and had a good CT scan in June. But in the last month his WBC, neutrophils and platelets have fallen drastically
kathymac52
in CLL Support

Shingles

I have had an attack of shingles on my thorax, treated with acyclovir. It started 2 weeks ago. The spots have all cleared, although the skin is quite tender still. But I feel really tired and unwell, which I wasn’t expecting 2 weeks on. I keep wondering if this is only the CLL or whether I should start
I have had an attack of shingles on my thorax, treated with acyclovir. It started 2 weeks ago. The spots have all cleared, although the skin is quite tender still. But I feel really tired and unwell, which I wasn’t expecting 2 weeks on. I keep wondering if this is only the CLL or whether I should start
Thinkimjob
in CLL Support

Stopping Ibrutinib?

Husband has been on Ibrutinib for 2 years and numbers were good until about 4 months when his WBC and Neutrophils dropped dramatically. WBC is now 2.2 and neutrophils are .8. Doctor suspended his meds for a week because he is concerned about COVID-19. I am worried that the CLL will roar back. He will
Husband has been on Ibrutinib for 2 years and numbers were good until about 4 months when his WBC and Neutrophils dropped dramatically. WBC is now 2.2 and neutrophils are .8. Doctor suspended his meds for a week because he is concerned about COVID-19. I am worried that the CLL will roar back. He will
kathymac52
in CLL Support

Remission, Day 4: Online Dating Question

I'm leaving this post unlocked. I don't know if people from other communities in HealthUnlocked can see and reply, but if you can, please do from the perspective of your own chronic illness or disease. The Dana-Farber AVO trial ended for me this week. MRD-, partial response (a single lymph node was
I'm leaving this post unlocked. I don't know if people from other communities in HealthUnlocked can see and reply, but if you can, please do from the perspective of your own chronic illness or disease. The Dana-Farber AVO trial ended for me this week. MRD-, partial response (a single lymph node was
Lily_Pad_Master
in CLL Support
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