Acyclovir is an antiviral medicine effective against herpes simplex and varicella zoster viruses. It does not cure infections caused by these viruses but helps to minimize the symptoms and shorten the duration of infection. It does not remove the viruses from the body but prevents the viruses from dividing and spreading.

No, you can infect other people, even while you are being treated with Acyclovir. Herpes infections are contagious, so avoid letting infected areas come into contact with other people. Avoid touching your eyes after touching an infected area. Wash your hands frequently to prevent transmitting the infection to others. You should practice safe sex by using condoms. You should not have sex if you have genital sores or blisters.

Serious side effects are rare, but if you experience them, you should seek medical advice right away. These rare side effects include hives, blistering or peeling rash, yellow skin or eyes, unusual bruising or bleeding, loss of consciousness, fits, difficulty in breathing, hallucinations and swelling of the face, tongue, lips or throat.

Older adults (over age 65 years) tend to experience more side effects when taking Acyclovir. The reason being, their kidneys do not flush the drug out of their system as quickly as a younger person’s kidneys would do. Elderly patients should drink plenty of water while taking Acyclovir, and their kidney function should be monitored. These patients should be given a lower dose and should be monitored for neurological problems.

Accidental, repeated overdoses of oral Acyclovir over several days have resulted in nausea, vomiting, confusion and headache. Consult your doctor in case of overdose.

Patients with advanced HIV disease or patients with an impaired immunity have reported resistance to Acyclovir. If you are not responding to Acyclovir, the possibility of drug resistance should be checked.

Hair loss is an uncommon side effect of Acyclovir. It stops when the medicine is discontinued.