Side effects | Aciclovir

Side effects

Aciclovir is generally well tolerated. Nevertheless, side effects may occur both with short-term use and with long-term use of the drug that has become necessary. The more frequent side effects when using ointments in the skin area include reddening and irritation of the skin, scaling, dry skin and itching or burning.

When using Aciclovir as an infusion or as a tablet, itching, hives (skin rash), nausea, vomiting, abdominal pain, diarrhea, headache, malaise and fatigue may also occur. In some cases, blood count changes were also observed during prolonged acyclovir treatment, but these decreased again after the drug was discontinued. These included anemia, reduced platelet count and reduced white blood cells.

Very rarely high fever and inflammatory reactions, kidney pain, breathing difficulties, liver inflammation with accompanying jaundice (hepatitis) and neurological side effects such as speech or gait disorders, tremors, delusions and psychoses were observed while taking acyclovir. Some side effects made it necessary to stop taking the drug immediately. In case of slight itching or minor skin reactions, especially if the treatment has already been carried out for some time, it may be considered whether the acyclovir intake can still be stopped in order to achieve a final and lasting treatment success.


There are different dosages of acyclovir depending on the reason for taking it. In addition, the dose to be used depends on the patient’s age, height, weight and previous illnesses. Aciclovir is available in tablet form, as an infusion and as an ointment.

The dosage varies between 200 mg and 800 mg. In the case of herpes disease of the face or genital area, treatment in the form of a cream with the dosage of 200 mg acyclovir can be started. If the use of the cream is no longer sufficient, it is possible to switch to taking tablets.

For each dose in the form of a tablet, sufficient water should be drunk throughout the day. For the treatment of a herpes disease in the area of the face and genitals, tablets with a dosage of 200mg acyclovir, taken every fourth hour, i.e. five times a day, are suitable for otherwise healthy adults. The individual intakes can also be changed to, for example, a dose of 400mg taken twice a day.

This dosage can also be taken by patients who frequently suffer from severe herpes to prevent recurrence. Children from the age of two can receive the same dosage. Younger children are usually given half the dose.

People who have a congenital weakness of the immune system or a weakness caused by other drugs take a dose of 200mg daily at six-hour intervals as a preventive measure. If the immune system is very severely impaired, such as after a liver transplant, the single dose can be doubled to 400mg. In the case of an infection with the Herpes Zoster Virus, which is responsible for shingles, a dose of 800mg is used consistently five times a day at regular intervals over a period of one week.

In cases of recurrent shingles, long-term treatment with Aciclovir can be considered to prevent secondary diseases such as nerve damage. Here, Aciclovir is used as a tablet in the dosage of 3x 500 mg over several months. In old age and in the presence of kidney disease, the dosage must be reduced in some cases.

This should always be discussed with the treating physician. If Aciclovir is used as an infusion, a dose of 5-10 mg per kilogram of the patient’s body weight is given into the vein three times a day. All doses used to treat an acute disease should be administered for about five days. The application is similar to taking antibiotics. It is therefore essential to ensure that acyclovir is taken until the end, even after the symptoms have subsided (e.g. in the case of shingles).