Valtrex

Why should Valtrex not be prescribed?

Avoid Valtrex if you are sensitive to it or the similar drug acyclovir (Zovirax).

Special warnings about Valtrex

High doses of Valtrex have proved dangerous in people whose immune system is compromised because of HIV infection, bone marrow transplant, or kidney transplant.

If your kidneys are not functioning properly, or you are taking drugs that may damage the kidneys such as Neomycin or Streptomycin, Valtrex can make your condition worse or affect your central nervous system (brain and spinal cord).

Effects on the central nervous system are more common in older adults, leading to such symptoms as agitation, confusion, and hallucinations. Their kidneys are also more likely to be affected; and those with kidney problems need a smaller dose. In addition, older adults tend to suffer the pain of shingles for a longer time after healing has begun.

Valtrex relieves the symptoms of genital herpes, but it is not a cure. There's also no evidence that it will prevent transmission of the disease. To avoid spreading the infection, don't have sexual intercourse during a flare-up.

Valtrex is not intended for use in children.

Possible food and drug interactions when taking Valtrex

If you are taking Valtrex with certain other drugs, the effect of either drug could be increased, decreased, or altered. Check with your doctor before combining Valtrex with cimetidine (Tagamet) and/or probenecid (Benemid).

Special information if you are pregnant or breastfeeding

The effects of Valtrex during pregnancy and breastfeeding have not been adequately studied. If you are pregnant or plan to become pregnant, notify your doctor immediately. If you are nursing and need to use Valtrex, your doctor may advise you to discontinue breastfeeding while using the medication.

Recommended dosage

SHINGLES

The usual dose is 1 gram 3 times a day for 7 days.

GENITAL HERPES

The usual dose for the first attack is 1 gram twice a day for 10 days. For later attacks, the dose is 500 milligrams twice a day for 3 days. To keep the condition from returning, the dose is 1 gram once a day. If you've had less than 10 infections per year, your doctor may prescribe 500 milligrams once a day. The safety and effectiveness of Valtrex treatment beyond 1 year have not been studied.

Patients with kidney problems or HIV infection may need a reduced dosage.

COLD SORES

The recommended dosage is 2 grams twice a day for 1 day, taken about 12 hours apart. Valtrex should not be taken for more than 1 day. The elderly and people with kidney problems may need a reduced dosage.

Overdosage

When taken by people with kidney disorders, excessive doses of Valtrex have been known to cause psychological problems and kidney failure. If you suspect an overdose, check with your doctor immediately.