Valacyclovir: Price, Dosage & Where to Buy

Valacyclovir is an antiviral medicine in the deoxynucleoside analogue DNA polymerase inhibitor class. It requires a prescription in the United Kingdom. It is most commonly prescribed to treat cold sores, genital herpes, shingles, and chickenpox.

Generic valacyclovir has been available since 31 January 2007. The brand name Valtrex is also used for this medicine.

Valacyclovir belongs to a class of medicines called deoxynucleoside analogue DNA polymerase inhibitors. After you swallow a tablet, the body converts valacyclovir into its active form, acyclovir. Acyclovir enters cells infected by herpes viruses.

Inside those cells, it interferes with the viral DNA polymerase enzyme that the virus needs to copy its genetic material. By blocking this enzyme, acyclovir stops the virus from multiplying.

This helps reduce the severity and duration of outbreaks, speeds healing of lesions, and lowers the amount of virus present. Valacyclovir does not eliminate the virus from the body permanently, but it controls active infections and reduces the frequency of recurrences when used for suppression.

Valacyclovir treats viral infections caused by herpes viruses. In adults, it is prescribed for cold sores on the lips, genital herpes (including initial episodes, recurrent outbreaks, and long-term suppression), shingles, and to reduce transmission of genital herpes to partners. In children aged 12 years and older, it treats cold sores.

In children aged 2 to under 18 years, it treats chickenpox. For genital herpes suppression, it is also used in adults with HIV-1 infection who have a CD4+ cell count of 100 cells per cubic millimetre or higher. Valacyclovir works against the herpes simplex viruses that cause cold sores and genital herpes, as well as the varicella-zoster virus that causes chickenpox and shingles.

The label lists 500 mg and 1 g tablets in oral and film-coated forms. For cold sores in adults and children aged 12 years and older, the usual dose is 2 grams every 12 hours for 1 day. For initial genital herpes in adults, the label lists 1 gram twice daily for 10 days.

For recurrent genital herpes, the usual dose is 500 mg twice daily for 3 days. For suppressive therapy in adults with normal immune function, the label lists 1 gram once daily, or 500 mg once daily in those with 9 or fewer recurrences per year. In adults with HIV-1 infection, the suppressive dose is 500 mg twice daily.

To reduce transmission of genital herpes, the label lists 500 mg once daily. For shingles in adults, the usual dose is 1 gram 3 times daily for 7 days. For chickenpox in children aged 2 to under 18 years, the label lists 20 mg per kilogram 3 times daily for 5 days, not to exceed 1 gram 3 times daily.

The label lists storage at 20 to 25 degrees Celsius. This corresponds to controlled room temperature. Keep valacyclovir tablets in their original container to maintain quality.

Store the medicine out of sight and reach of children. If an oral suspension is prepared from tablets, it must be refrigerated between 2 and 8 degrees Celsius and discarded after 28 days. Do not use any medicine past its expiry date.

The label does not provide specific guidance on missed doses for valacyclovir. If you miss a dose, contact your prescriber or pharmacist for advice. Do not double the next dose to make up for a missed one.

For short courses such as cold sore treatment, missing a dose may reduce how well the medicine works. For daily suppressive therapy, resume your usual schedule as soon as you remember. The timing of treatment is important for conditions like shingles and chickenpox, where therapy should start within 48 to 72 hours of symptom onset.

Clinical data over several decades with valacyclovir and its metabolite acyclovir in pregnant women have not identified a drug-associated risk of major birth defects. Insufficient data exist regarding miscarriage or adverse maternal or foetal outcomes. Pregnancy registries documented major birth defects in 4.5 per cent of first-trimester exposures to valacyclovir and 3.9 per cent of any-trimester exposures, though available studies have methodological limitations.

Untreated herpes simplex during pregnancy carries risks to the foetus, including neonatal infection rates of 30 to 50 per cent when genital herpes is acquired in late pregnancy. Animal studies at exposures several times the human dose showed no adverse developmental outcomes. Discuss the use of valacyclovir during pregnancy with your doctor or pharmacist.