Aciclovir: Well tolerated against herpes viruses

Itchy, painful blisters in the mouth area – every third German has had to deal with  cold sores  at some point. The drug of choice against this herpes is then usually a cream with the active ingredient aciclovir, which can alleviate the symptoms. But aciclovir is also effective against other diseases caused by herpes viruses – such as  shingles  or  genital herpes . We explain what you have to consider when treating with aciclovir and what side effects can occur.

Mode of action: Inhibition of virus replication

Aciclovir is what is known as a nucleoside analogue. This means that its chemical structure resembles a building block of the herpes virus DNA. If the virus multiplies in an infected human cell and doubles its DNA, the aciclovir molecule can be incorporated instead of the “correct” building block. This then leads to the virus replication being interrupted.

In this way, the active ingredient can alleviate and shorten the course of herpes infections. Aciclovir acts against the herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) and against the varicella zoster virus, which also belongs to the herpes virus group.

Application of aciclovir

Aciclovir is used in the following diseases caused by herpes viruses:

• Lippenherpes (Herpes labialis)
• Genitalherpes (Herpes genitalis)
• Shingles (herpes zoster)
• corneal inflammation of the eye
• inflammation of the brain  (encephalitis)

In addition, aciclovir can be used to prevent HSV infections in patients with a severely weakened immune system, for example after an organ transplant. More rarely, the active ingredient is also used to treat  chickenpox  (varicella) in immunocompromised people.

Aciclovir als Salbe

Aciclovir ointment is used to relieve pain and  itching associated  with cold sores and is available in pharmacies without a prescription. The cream should be applied to the affected area every four hours until the blisters crust over. The duration of treatment is usually five to a maximum of ten days. In addition, an aciclovir-containing ointment can be used to support the treatment of genital herpes.

To treat corneal inflammation caused by herpes viruses, there is a special  eye ointment that has to be prescribed by an ophthalmologist. During treatment, a strip of ointment about one centimeter long is usually placed in the lacrimal sac every four hours. The duration of treatment depends on the course of the disease – after the inflammation has healed, the ointment should be used for at least three more days.

Dosage of aciclovir

Depending on the disease to be treated, aciclovir can be used in various dosage forms and dosages: in the form of  tablets  with 200, 400 or 800 milligrams of active substance, aciclovir is used for genital herpes and shingles as well as for severe courses of corneal inflammation. Please follow the instructions given by your doctor or the package leaflet for dose and use!

In the case of genital herpes and corneal inflammation, 400 milligrams of aciclovir are usually taken three to four times a day, whereas shingles usually requires a higher dosage of up to 4,800 milligrams a day divided into six individual doses. The duration of treatment is usually seven to ten days, but it is important that therapy is started as soon as possible after the onset of symptoms.

Aciclovir als Prophylaxe

In particular, patients with a severely weakened  immune system , who are at increased risk of herpes infection, can be treated preventively with aciclovir. In addition, a prophylactic intake of aciclovir in patients with frequently recurring, severe genital herpes can be considered. The dose is usually between 400 and 1,600 milligrams per day.

Infusion therapy for serious illnesses

In severe illnesses such as encephalitis caused by herpes viruses, aciclovir can be given as an infusion. Infusion therapy with aciclovir can also be considered in the case of severely painful genital herpes or if severe complications such as  pneumonia  occur with chickenpox.

Herpes infections in immunocompromised patients are also often treated with aciclovir infusions. Compared to the application in the form of tablets, infusions are usually much more effective – however, a hospital stay is usually necessary.

Contraindications and Precautions

Aciclovir must not be used if you are hypersensitive to the active substance. Caution is advised in patients with renal impairment as aciclovir is excreted via the kidneys. Delayed excretion of aciclovir can therefore occur in the case of impaired renal function, which is why a lower dosage is usually required in these cases.

Aciclovir side effects

Aciclovir is a relatively well-tolerated active ingredient – side effects usually only occur with high doses or with infusion therapy. Because then crystals from the active ingredient can form in the urine and thereby damage the kidneys. Therefore, you should drink enough during treatment with aciclovir.

In addition, the following side effects may occur:

• Allergic reactions such as skin rash
• nausea  and vomiting
• headache  or dizziness
• Confusion, loss of consciousness or hallucinations
• Changes in the  blood count  as well as the liver values ​​and kidney values
• Burning, irritation or reddening of the skin or conjunctiva after topical treatment with an ointment or cream containing aciclovir.
• Irritation of the veins at the infusion site and inflammation – particularly if the infusion accidentally leaks into the tissue.

For a detailed list of possible side effects, please refer to the package leaflet.

Drug interactions

Drugs can influence each other if you take medications during treatment with aciclovir that affect kidney activity – for example probenecid (to treat  gout ), cimetidine (to reduce stomach acid) or theophylline (for respiratory diseases such as  asthma ). ).

In addition, interactions with aciclovir can occur during simultaneous treatment with the active ingredients mycophenolate mofetil and ciclosporin (used to suppress the immune system after transplantation). Therefore, always inform your doctor about all medications that you must take regularly!

Aciclovir in pregnancy and lactation

In animal studies, the use of aciclovir during pregnancy has resulted in fetal malformations. However, there is no evidence that the active substance also has harmful effects on the unborn child in humans. Since there are insufficient studies on this, the use of aciclovir during pregnancy should only take place after careful consideration of the benefits and risks.

However, it is known that aciclovir passes into breast milk. Therefore, aciclovir should not be used during breastfeeding. If treatment with aciclovir is necessary during breast-feeding, breast-feeding may be interrupted for the duration of the application.