Aciclovir tablets are used to treat infections with herpes viruses. The herpes viruses include the viruses that cause cold sores and genital herpes (herpes simplex 1 and 2)
Aciclovir works by stopping the herpes virus from reproducing and infecting more cells in the body. It is converted to a more active form inside the infected cells of the body. The activated aciclovir then works by blocking the action of a viral enzyme called DNA polymerase thus preventing the virus from multiplying. This controls the infection and helps the body’s immune system to deal with it.
Aciclovir is taken by mouth to treat genital herpes and other herpes simplex infections of the skin and mucous membranes. It is also used to prevent these infections coming back in people who suffer recurrent infections.
Oral aciclovir is also valuable for preventing herpes simplex infections in people whose immune systems are suppressed and cannot fight off infection, either due to disease, e.g. HIV and AIDS, or medical treatment, e.g. chemotherapy, steroids, bone marrow transplant.
Adults should use the following regimens for the treatment of an infection:
- One 200mg tablet 5 times a day at 4 hourly intervals for 5 days
- One 400mg tablet 3 times a day at 8 hourly intervals for 3 to 5 days
- One 200mg tablet 4 times a day for 6 to 12 months
- One 400mg tablet twice a day for 6 to 12 months
If your immune system is severely impaired or you have impaired absorption from the gut, the dose may need to be increased. If this is the case please consult a doctor.
Medicines and their possible side effects can affect individual people in different ways. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect. The following are some of the side effects that are known to be associated with acyclovir:
- Nausea and vomiting.
- Abdominal pain.
- Skin reactions such as rash and itch.
- Abnormal reaction of the skin to light, usually a rash (photosensitivity).
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with aciclovir, please read the information provided with the medicine or consult your doctor or pharmacist.
Genital herpes is a sexually transmitted disease. The risk of passing the infection on to your sexual partner is greatest when you have active symptoms of the infection.
There is still a risk of passing the infection on if you use condoms, and even if you are taking this medicine to help control the infection.
It is therefore important that you avoid having sex while you have symptoms, even if you are taking this medicine to treat the infection.
Aciclovir should be used with caution in:
- Elderly people.
- Decreased kidney function.
Aciclovir should NOT be used in:
- Allergy to aciclovir or valaciclovir.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using aciclovir and inform your doctor or pharmacist immediately.
The patient information leaflet (PIL) is a leaflet containing specific information about medical conditions, doses and side effects. You can download a copy of the PIL here:
Patient Info Leaflet