Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Valtrex

Descriptions


Valacyclovir is used to treat herpes virus infections, including herpes labialis (also known as cold sores), herpes zoster (also known as shingles), and herpes simplex (also known as genital herpes) in adults. It is also used to treat chickenpox and cold sores in children.

In your body, valacyclovir becomes the anti-herpes medicine, acyclovir. Although valacyclovir will not cure shingles or genital herpes, it does help relieve the pain and discomfort and helps the sores heal faster.

Valacyclovir is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Tablet

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of valacyclovir in children below 12 years of age with cold sores, and children below 2 years of age with chickenpox. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of valacyclovir in the elderly. However, elderly patients are more likely to have age-related kidney disease, which may require an adjustment in the dose of patients receiving valacyclovir.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Dichlorphenamide
  • Emtricitabine
  • Fexinidazole
  • Foscarnet
  • Leflunomide
  • Nitisinone
  • Tenofovir Alafenamide
  • Teriflunomide

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Fosphenytoin
  • Phenytoin
  • Valproic Acid

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Advanced human immunodeficiency virus (HIV) infection or
  • Bone marrow transplantation or
  • Kidney transplantation—Patients with these medical problems may have an increased risk of severe side effects.
  • Kidney disease—The effects may be increased because of slower removal of this medicine from the body.

Proper Use

Valacyclovir works best if it is used within 48 hours after the first symptoms of shingles or genital herpes (e.g., pain, burning, or blisters) begin to appear. For recurrent outbreaks of genital herpes, valacyclovir works best if it is used within 24 hours after the symptoms begin to appear.

If you are taking valacyclovir for the treatment of chickenpox, it is best to start taking valacyclovir as soon as possible after the first sign of the chickenpox rash appears, usually within one day.

Valacyclovir may be taken with meals or on an empty stomach.

If you are using the oral suspension, use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

Drink extra fluids so you will pass more urine while you are using this medicine. This will keep your kidneys working well and help prevent kidney problems.

To help clear up your infection, keep taking valacyclovir for the full time of treatment, even if your symptoms begin to clear up after a few days. Do not miss any doses. However, do not use this medicine more often or for a longer time than your doctor ordered.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For treatment of chickenpox:
      • Adults and children below 2 years of age—Use and dose must be determined by your doctor.
      • Children 2 to 18 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 20 milligrams (mg) per kilogram (kg) of body weight, taken three times a day for 5 days. However, the dose is usually not more than 1000 mg three times a day.
    • For treatment of cold sores:
      • Adults—2000 milligrams (mg) every 12 hours for one day.
      • Children 12 years of age and above—2000 milligrams (mg) every 12 hours for one day.
      • Children below 12 years of age—Use and dose must be determined by your doctor.
    • For treatment of genital herpes, first outbreak:
      • Adults—1000 milligrams (mg) two times a day for ten days.
      • Children—Use and dose must be determined by your doctor.
    • For treatment of genital herpes, recurrent outbreaks:
      • Adults—500 milligrams (mg) two times a day for three days.
      • Children—Use and dose must be determined by your doctor.
    • To prevent recurrent outbreaks of genital herpes:
      • Adults—500 milligrams (mg) or 1000 mg once a day.
      • Children—Use and dose must be determined by your doctor.
    • For treatment of shingles:
      • Adults—1000 milligrams (mg) three times a day for seven days.
      • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions

If you or your child's symptoms do not improve within a few days, or if they become worse, check with your doctor.

The areas affected by genital herpes, chickenpox, or shingles should be kept as clean and dry as possible. Also, wear loose-fitting clothing to avoid irritating the sores (blisters).

It is important to remember that this medicine will not keep you from spreading herpes to others.

Herpes infection of the genitals can be caught from or spread to your partner during any sexual activity. Even though you may get herpes if your partner has no symptoms, the infection is more likely to be spread if sores are present. This is true until the sores are completely healed and the scabs have fallen off. Therefore, it is best to avoid any sexual activity if either you or your sexual partner has any symptoms of herpes. The use of a latex condom (“rubber") may help prevent the spread of herpes. However, spermicidal (sperm-killing) jelly or a diaphragm will probably not help.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  1. Discouragement
  2. feeling sad or empty
  3. irritability
  4. lack of appetite
  5. loss of interest or pleasure
  6. tiredness
  7. trouble concentrating
  8. trouble sleeping

Rare

  1. Black, tarry stools
  2. chest pain
  3. chills
  4. cough
  5. decreased frequency or output of urine
  6. fever
  7. flu-like symptoms
  8. headache
  9. lower back or side pain
  10. reduced mental alertness
  11. shortness of breath
  12. yellow eyes or skin

Incidence not known

  1. Actions that are out of control
  2. agitation
  3. anxiety
  4. back, leg, or stomach pains
  5. bleeding gums
  6. blood in urine or stools
  7. blurred vision
  8. change in consciousness
  9. change in mental status
  10. changes in behavior, especially in interactions with other people
  11. changes in patterns and rhythms of speech
  12. dark or bloody urine
  13. difficult or labored breathing
  14. difficulty speaking
  15. difficulty swallowing
  16. dizziness
  17. drowsiness
  18. dry mouth
  19. fast, pounding, or irregular heartbeat or pulse
  20. feeling that others are watching you or controlling your behavior
  21. feeling that others can hear your thoughts
  22. feeling, seeing, or hearing things that are not there
  23. general tiredness and weakness
  24. hyperventilation
  25. increased thirst
  26. itching
  27. lightheadedness when getting up from a lying or sitting position
  28. light-colored stools
  29. loss of consciousness
  30. mood or mental changes
  31. nausea and vomiting
  32. nervousness
  33. pale color of skin
  34. pinpoint red spots on the skin
  35. pounding in the ears
  36. puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  37. redness of the skin
  38. restlessness
  39. seeing, hearing, or feeling things that are not there
  40. seizures
  41. severe mood or mental changes
  42. shakiness and unsteady walk
  43. shakiness in the legs, arms, hands, or feet
  44. skin rash
  45. slurred speech
  46. sores, ulcers, or white spots on the lips or in the mouth
  47. stiff neck
  48. swelling of the face, fingers, or lower legs
  49. swollen or painful glands
  50. talking, feeling, and acting with excitement
  51. tightness in the chest
  52. trembling or shaking of the hands or feet
  53. trouble in speaking
  54. troubled breathing
  55. unsteadiness, trembling, or other problems with muscle control or coordination
  56. unusual behavior
  57. unusual bleeding or bruising
  58. unusual tiredness or weakness
  59. upper right abdominal pain
  60. vomiting
  61. weight gain
  62. wheezing

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Body aches or pain
  2. cramps
  3. difficulty in moving
  4. ear congestion
  5. heavy bleeding
  6. loss of voice
  7. muscle aches
  8. muscle pain or stiffness
  9. nasal congestion
  10. pain
  11. pain in joints
  12. sneezing
  13. sore throat
  14. stuffy or runny nose

Less common

  1. Constipation
  2. diarrhea

Incidence not known

  1. Blistering, peeling, or loosening of the skin
  2. hair loss or thinning of the hair
  3. hives or welts
  4. increased sensitivity of skin to sunlight
  5. red, irritated eyes
  6. redness or other discoloration of the skin
  7. severe sunburn

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Portions of this document last updated: Feb. 01, 2024

Original article: https://www.mayoclinic.org/zh-hans/drugs-supplements/valacyclovir-oral-route/before-using/drg-20066635