Aciclovir is an antiviral medication used to treat infection caused by herpes viruses, including cold sores, genital herpes, chickenpox and shingles. It is available on prescription as an oral medication, or as a topical cream which can be bought over the counter, prescription-free. It can also be used as a long-term suppressive therapy to reduce the frequency, duration and severity of outbreaks of symptoms.
People experiencing recurrent outbreaks of genital herpes or cold sores may choose to take aciclovir tablets for a period of 6–12 months to reduce the risk of symptomatic outbreaks. When used in this way, viral shedding is also reduced, which means you will be less contagious. However suppressive therapy with aciclovir does not guarantee you will not still experience outbreaks and does not eliminate viral shedding completely.
When taken for symptomatic relief, aciclovir is most effective if taken within 48–72 hours of the onset of symptoms, and should be started within 5 days. Symptoms usually start to subside within 3 days of taking the medication, however, the sores caused by initial herpes infection can take up to three weeks to completely disappear. Recurrent outbreaks of herpes tend to be much shorter in duration. Use of aciclovir can shorten the duration of an outbreak by 1–2 days.
When taken as a long-term suppressive therapy, significant suppression of viral replication and shedding is achieved within 5 days. However, it is important to know that viral shedding is not completely eliminated by the use of aciclovir, so you may still be able to pass on the virus.
Aciclovir reduces the frequency, severity and duration of outbreaks of herpes. As herpes is most contagious when symptoms are present, the use of aciclovir will reduce the risk of transmission of the virus to others. However herpes can be transmitted even when symptoms are not present, so it is important to be aware that aciclovir does not eliminate the risk of transmission. Therefore, it is recommended that you avoid sexual contact while genital sores are present, and avoid kissing while oral sores are present.
200mg, 5 times per day
|Type of Medicine||
Competitively inhibits and inactivates viral DNA processes, preventing replication
15, 30, 45 or 168 tablets
From 21p per tablet
Can include nausea, vomiting, diarrhoea, headaches, stomach pains, feeling dizzy, feeling tired, fever, itching, skin rash
The active ingredient in aciclovir tablets is aciclovir - an antiviral agent.
The inactive ingredients of aciclovir tablets may include: magnesium stearate, microcrystalline cellulose, sodium starch glycollate, pregelatinised starch and colloidal anhydrous silica.
Please note: different brands of aciclovir may contain different inactive ingredients
Aciclovir can cause a severe allergic reaction in people presenting as facial/lip swelling, a rash/hives, severe dizziness and trouble breathing. However, the incidence of a severe allergic reaction is rare. However, if you notice any of the symptoms listed above after taking this anti-retroviral drug, please visit your local emergency department to get immediate medical attention.
You should start your treatment as soon as possible. Aciclovir tablets can be swallowed whole with water. If you have trouble swallowing the tablets, they can be dissolved in a glass of water and stirred before drinking. Aciclovir should be taken for a minimum of five days, and for the duration recommended by the prescribing doctor. If you miss a tablet, take it as soon as you remember, however, if it is only a few hours until your next dose, skip the missed dose. Do not take a ‘double dose’ to make up for a missed dose.
For the treatment of an initial outbreak or recurrence of oral or genital herpes, the usual dose is 200mg five times per day. This is usually recommended for a duration of 5 days.
When used for suppression of oral or genital herpes, the usual dose is 200mg four times per day. This is usually continued for 6–12 months.
Yes, aciclovir can be split, crushed or dispersed in water.
If you struggle to swallow aciclovir tablets, they can be dispersed in a glass of water. One 200mg tablet should be dissolved in at least 50ml of water, stirred and swallowed.
Common side effects of aciclovir tablets include:
Rare side effects of aciclovir tablets are:
If you experience any severe side effects or symptoms of an allergic reaction (breathing difficulties, swelling, itching, hives, rash) you should seek immediate medical attention.
If you experience any prolonged side effects you should speak to the prescribing doctor.
You should not use aciclovir if you are allergic to aciclovir or valaciclovir. If you are taking any other medication, if you are pregnant or breastfeeding, or if you have any other health conditions, particularly kidney or liver problems, you should inform the prescribing doctor as this medication may not be suitable.
You should also inform the prescribing doctor if you are over the age of 65, or have a weakened immune system.
You should inform the prescribing doctor if you are taking, have taken or are planning on taking any other medications, including over the counter (non-prescription) medications, herbal remedies and recreational drugs.
Aciclovir is not known to be harmful during pregnancy and is often prescribed to pregnant women for the treatment or suppression of herpes. However, if you are pregnant, there is a chance you may be pregnant, or you plan on becoming pregnant you should disclose this to the prescribing doctor.
Aciclovir is passed into the breast milk of breastfeeding women. It is not thought to be harmful to the infant, however, if you are breastfeeding and require aciclovir, it is important to disclose this to the prescribing doctor.
Aciclovir is available as a topical cream, which can be purchased over the counter without a prescription. Topical creams may be useful for the self-management of oral herpes, but are not recommended for the treatment of genital herpes and should not be used in the vagina or anus.
Oral aciclovir tablets are only available on prescription and are recommended for use for the treatment or suppression of oral and genital herpes.
Herpes does not necessarily require treatment and the vast majority of cases can be managed at home without prescription medication. There are several measures you can take at home to help your body to heal:
Aciclovir is not an antibiotic. Antibiotics are used to treat bacterial infections. Herpes is a viral infection and aciclovir is an antiviral medication.
Human papillomavirus (HPV) infection typically causes warts, including genital warts. It does not cause genital herpes. Aciclovir will not treat HPV infection as the virus replicates in a different way from the herpes simplex viruses that cause herpes infection.
If you are worried you may have genital warts, you should see your doctor for diagnosis and treatment. You can also be tested for infection with HPV even if you have no symptoms.
Some strains of HPV are associated with the development of cancers such as cervical cancer, anal cancer and some oral and throat cancers. To reduce the risk of these cancers, the UK NHS introduced a nationwide HPV vaccination programme to school children and at-risk adults. Adults can also obtain the vaccination using a private prescription.
Shingles is caused by another type of human herpesvirus, the varicella-zoster virus, and results in a painful skin rash. Aciclovir can be used to treat shingles, however, the dose is usually different to that used for oral or genital herpes. In shingles, aciclovir is most effective when taken within the first 72 hours of symptoms.
If you think you have shingles, it is important to contact your doctor for an accurate diagnosis and treatment.
Aciclovir can be found in blood and urine when a person is taking the drug, and for several days after completing treatment. As aciclovir is excreted by the kidneys into the urine, it may affect levels of other drugs also processed in this way. There is no evidence that taking Aciclovir will cause you to test positive for substances such as opiates, cannabinoids, alcohol, amphetamines, benzodiazepines or cocaine. If you are taking aciclovir and are worried about drug testing, speak to the prescribing doctor for more information.