Brand names: Valtrex
Valtrex is used to treat certain herpes infections, including herpes zoster (the painful rash known as shingles), genital herpes, and herpes cold sores on the face and lips.
Valtrex should not be used by anyone with a weak immune system, such as those with HIV infection or those who have undergone a bone marrow or kidney transplant. Valtrex can cause serious side effects, including death, in such people.
If you are taking Valtrex for shingles, you should start using it as soon as possible after your doctor has made a diagnosis. It's best to see a doctor and start the drug within 48 hours of first noticing the rash. If you wait more than 72 hours after you first get a herpes zoster rash, the medication may not be effective.
If you are using Valtrex for genital herpes, begin taking it at the first sign of an attack. The medication may not be effective if you wait longer than 72 hours after the first attack or 24 hours after a later attack.
If you are taking Valtrex for cold sores, you should start using it at the earliest signs of infection, such as tingling, itching, or burning. If you wait until the cold sore develops, the medication might not work.
You may take Valtrex with or without food.
Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue using Valtrex.
Avoid Valtrex if you are sensitive to it or the similar drug acyclovir (Zovirax).
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.
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).
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.
The usual dose is 1 gram 3 times a day for 7 days.
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.
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.
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.