About Valtrex
This medication is used in the treatment of genital herpes infections, and shingles (herpes zoster). It works by inhibiting the reproduction of the herpes virus. Valtrex (valacyclovir) does not cure herpes, but decreases the number of outbreaks and helps sores heal faster.
Valtrex treatment should begin within 24 hours of the first
signs of a genital herpes outbreak, and within 48 hours
of a shingles outbreak for maximum effectiveness. If you wait
more than 72 hours to start treatment this medication may
not be effective. Individuals with recurrent genital herpes
are sometimes prescribed daily doses to decrease the number
of outbreaks. If daily treatment is undertaken for recurrent
outbreaks, treatment should be re-evaluated after a year.
Valtrex is only available by prescription. Your doctor may
advise kidney function tests while you are taking this medication,
use only as directed.
Valtrex Side Effects
Common Side Effects:Abdominal pain, dizziness, headache, nausea, and vomiting.
Less Common or Rare: Acne, aggression, agitation, allergic reaction, confusion, depression, diarrhea, fatigue, hair loss, hallucinations, hepatitis, high blood pressure, increased heart rate, insomnia, joint pain, mania, menstrual problems, muscle cramps, nervousness, and swelling of the face. Contact your doctor immediately if side effects are severe.
Cautions: Valtrex may not be a suitable treatment
for all individuals. Speak to your doctor if any of the following
conditions apply to you, as altered dosage, additional monitoring,
or alternative treatments may be necessary.
- Allergy: Notify your doctor and pharmacist of any drug allergies. Do not take Valtrex if you are allergic to it or if you are allergic to Zyloprim (allopurinol).
- Bone Marrow Transplant: Do not use Valtrex if you have had a bone marrow transplant. It may lead to serious side effects or death.
- Dehydration: Avoid dehydration while taking Valtrex.
- HIV Infection: Do not take Valtrex if you have an HIV infection. May lead to severe side effects and fatality.
- Intercourse: Valtrex treats symptoms, but does not cure herpes. To decrease the chance of spreading the virus, avoid sexual intercourse while sores are present.
- Kidney Damage or Disease: Notify your doctor of kidney problems. You may need a dosage adjustment.
- Kidney Transplant: If you have had a kidney transplant, you should not take Valtrex. May result in acute side effects and possibly death.
- Liver Cirrhosis: Do not take Valtrex if you have cirrhosis of the liver.
- Nervous System Disorders: Discuss nervous system disorders with your doctor.
- Weak Immune System: Do not take Valtrex if you have problems with your immune system. It may lead to serious side effects and death.
- Zovirax (acyclovir): Do not take Valtrex if you have sensitivity to Zovirax.
Valtrex Interactions
Certain drugs react with Valtrex. Your doctor may adjust the dosage of one of the medications, or may indicate that they should not be taken together. Always consult your doctor or pharmacist about potential drug interactions.
- Alcohol - May increase dizziness.
- AZT (zidovudine) - May cause lethargy and acute fatigue.
- Benemid (probenecid) - If you are taking Benemid, notify your doctor before taking Valtrex.
- Cerebyx (fosphenytoin) - Valtrex may decrease the effectiveness of Cerebyx.
- Demerol (meperidine) - May cause neurological problems when combined.
- Depakote (valproic acid) - Valtrex may lower the effectiveness of Depakote.
- Dilantin (phenytoin) - Valtrex may decrease the effectiveness of Dilantin.
- Neomycin - Combining Valtrex with Neomycin may damage kidneys or affect central nervous system.
- Sandimmune (cyclosporine) - May increase risk of kidney toxicity.
- Streptomycin - May cause kidney damage or affect the central nervous system when combined with Valtrex.
- Tagamet (cimetidine) - If you take Tagamet, notify your doctor before taking Valtrex.
- Varivax (varicella vaccine) - Valtrex may lower the effects of Varivax.
- Zyloprim (allopurinol) - If you are allergic to Zyloprim, you may have an allergic reaction if you take Valtrex.
Valtrex Dosages
Valtrex is available in 500 mg and 1 gram tablets. The general guidelines for adults are as follows:
- Shingles (herpes zoster); Usually 1 gram 3 times per day for 7 days.
- Genital Herpes Outbreak; for the first outbreak the usual dosage is 1 gram two times per day for 10 days. For subsequent outbreaks the usual dose is 500 mg two times a day for 3 days. Suppressive Therapy; May be 500 mg or 1 g per day for up to one year followed by re-evaluation.
Your doctor may suggest a different dosage or frequency of use. Always follow the instructions on your prescription, taking your medication as often, and for as long, as suggested by the prescribing physician.
If you have kidney function problems, your doctor may prescribe a reduced dose or direct you to discontinue treatment. Signs of overdose include psychological problems and kidney failure.
Valtrex Directions
Start treatment as soon as possible, preferably within one day, of a herpes or shingles outbreak. If you miss a dose, take it as soon as you remember. If it's nearly time for your next dose, skip the missed dose and resume your regular schedule. Do not take double doses, or change your dose without permission from your doctor. Tablets may be taken with or without food.
Take this medication for as long as your doctor recommends, even if you begin to feel better. Viral infections may still linger even if the obvious symptoms have gone away. Still, you should not continue treatment for any longer than your doctor suggests. If you see no improvement towards the end of your treatment, contact your doctor for further instructions.
Store Valtrex away from direct light and heat. Store tablets at room temperature in a dry location; avoid storing them in the bathroom, near sinks, or other areas where the container may become damp. Do not use after the expiration date.
Keep Valtrex away from children; both when storing it, and when discarding any unused medication.
Valtrex and Pregnancy
Notify your doctor if you are pregnant or plan to become pregnant. The effects of Valtrex on the fetus are not known. The use of this medication during pregnancy should be discussed with a doctor, and only undertaken if the benefits of treatment outweigh the possible risks to the infant.
This medication appears in breast milk. Discuss the risks with your doctor.
Valtrex and Children
Valtrex is not recommended for use in children.
Valtrex and Seniors
Seniors should avoid dehydration while taking Valtrex. Your doctor may prescribe a lower dose if you have kidney problems.
Valtrex is a trademark of Glaxo-Wellcome
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This document is provided for information only. It is not a substitute for consultation with a physician, either to diagnose symptoms or prescribe treatment. Any dosages mentioned are general guidelines only, please follow the directions of your doctor or pharmacist exactly when taking medication. We have made every effort to ensure that this information is accurate, but only your doctor can say if a medication, or drug combination, is safe for you. Information intended for US residents only.
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