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Fact Table
| Fact Table | |
|---|---|
| Formula | C13H20N6O4·HCl (valacyclovir hydrochloride); C13H20N6O4 (valacyclovir base) |
| License | FDA approved (NDA 020487; initial U.S. approval 1995); Health Canada marketed/approved (DINs 02219492, 02246559) |
| Bioavailability | Acyclovir absolute bioavailability after oral VALTREX is 54.5% ± 9.1%; not altered by food |
| Legal status | Prescription only (Rx-only); DEA Schedule: None |
| Chemical Name | L-valine, 2-[(2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)methoxy]ethyl ester, monohydrochloride |
| Elimination half-life | Acyclovir plasma elimination half-life after VALTREX averages 2.5–3.3 hours in adults with normal renal function |
| Dosage (Strength) | 500 mg and 1 g oral tablets. Adult regimens include 2 g every 12 hours for 1 day for cold sores; 1 g twice daily for 10 days for initial genital herpes; 500 mg twice daily for 3 days for recurrent genital herpes; 500 mg to 1 g once daily for suppression; 1 g three times daily for 7 days for herpes zoster |
| Pregnancy | Clinical data over several decades have not identified a drug-associated risk of major birth defects; insufficient data for miscarriage or other adverse maternal/fetal outcomes |
| Brands | Valtrex, Zelitrex; generics available |
| Protein binding | Valacyclovir 13.5–17.9%; acyclovir 9–33% |
| PubChem CID | 135398742 (valacyclovir); 135398741 (valacyclovir hydrochloride) |
| MedlinePlus | a695010 |
| ChEBI | 35854 (valacyclovir); 9919 (valacyclovir hydrochloride) |
| ATC code | J05AB11 |
| DrugBank | DB00577; DBSALT000289 (valacyclovir hydrochloride) |
| KEGG | D00398 (valacyclovir hydrochloride); D08664 (valacyclovir); C07184 |
| Routes of administration | By mouth (oral tablets; extemporaneous oral suspension prepared from tablets) |
Valtrex (valacyclovir) is a prescription antiviral tablet used to treat cold sores, genital herpes, and shingles. It works by stopping the herpes virus from multiplying, which may help sores heal faster, reduce symptom severity, and lower the chances of future outbreaks. It comes as an oral tablet and is one of the most commonly prescribed antiviral medications.
Directions
Take Valtrex exactly as prescribed by your doctor or healthcare provider. The dose depends on the condition being treated. For cold sores, the typical adult dose is 2 grams taken every 12 hours for one day (two doses total). For a first episode of genital herpes, the usual dose is 1 gram twice daily for 10 days. For recurrent genital herpes outbreaks, take 500 mg twice daily for 3 days. For long-term suppression of genital herpes, the dose is usually 1 gram once daily or 500 mg once daily depending on frequency of outbreaks.
For shingles, the dose is 1 gram three times daily for 7 days. Valtrex can be taken with or without food. Drink plenty of fluids while taking this medication to keep your kidneys working well. Start treatment as early as possible after symptoms appear for best results.
Ingredients
The active ingredient in Valtrex is valacyclovir hydrochloride, which is converted to acyclovir in the body. Inactive ingredients may include carnauba wax, colloidal silicon dioxide, crospovidone, FD and C Blue No. 2 Lake, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, povidone, and titanium dioxide.
Cautions
Before using this medication, you may want to consult a healthcare provider about the following:
- Any existing health conditions
- Any allergies
- A list of all medications currently being taken
Valtrex may cause kidney problems, especially in older adults, those with existing kidney disease, or those not drinking enough fluids. Your doctor may adjust your dose based on how well your kidneys are working.
In rare cases, a serious condition called thrombotic thrombocytopenic purpura/hemolytic uremic syndrome, also known as TTP/HUS, has been reported in patients with weakened immune systems, such as those with advanced HIV or organ transplant recipients.
Valtrex may cause nervous system side effects, such as confusion, agitation, hallucinations, or seizures, particularly in elderly patients or those with kidney problems. Contact your doctor if you experience any of these symptoms.
Serious skin reactions have been reported with valacyclovir. Stop taking Valtrex and seek medical attention if you develop a painful rash, blistering, or sores in the mouth, eyes, or genitals.
Contraindications
Avoid taking or using this medication if any of the following apply:
- You have had a serious allergic reaction, such as anaphylaxis or a severe skin reaction, to valacyclovir, acyclovir, or any of the ingredients in Valtrex
Side Effects
Common side effects of Valtrex include:
- Headache
- Nausea
- Abdominal pain
- Dizziness
- Vomiting
Serious side effects are rare but can include allergic reactions, such as hives, swelling of the face or throat, and difficulty breathing, kidney problems, unusual bruising or bleeding, confusion, hallucinations, and severe skin reactions.
Seek medical attention immediately if you experience any of these.
Frequently Asked Questions about Valtrex
What is Valtrex?
Valtrex is a brand-name oral antiviral medication that contains valacyclovir hydrochloride. Valacyclovir is converted in the body to acyclovir, which helps fight certain herpes viruses.
What is Valtrex used for?
Valtrex is used to treat cold sores, genital herpes, and shingles in adults. It is also used for cold sores in children 12 years and older and chickenpox in children 2 to under 18 years old.
Does Valtrex cure herpes?
No. Valtrex can help treat and control herpes outbreaks, but it does not cure herpes infections or remove the virus from the body. People with genital herpes can still transmit the virus even when symptoms are not present.
How does Valtrex work?
Valtrex works by slowing the multiplication of herpes viruses in the body. This can help reduce symptoms, shorten outbreaks, and, in some cases, reduce the risk of spreading genital herpes when used with safer sex practices.
How is Valtrex usually taken?
Valtrex is taken by mouth, usually as a tablet, with or without food. The dose and length of treatment depend on the condition being treated, such as cold sores, shingles, an initial genital herpes episode, recurrent outbreaks, or suppressive therapy.
When should Valtrex be started?
Valtrex generally works best when started as early as possible after symptoms begin. For cold sores, treatment is most effective when started at the first symptom, such as tingling, itching, or burning, before the sore fully develops.
What are common side effects of Valtrex?
Common side effects may include headache, nausea, stomach pain, vomiting, dizziness, and tiredness. Most side effects are mild, but persistent or bothersome symptoms should be discussed with a healthcare professional.
What serious side effects can Valtrex cause?
Serious but less common risks can include kidney problems, confusion, hallucinations, agitation, seizures, severe allergic reactions, and rare blood disorders in certain high-risk patients. Older adults, people with kidney disease, and people taking high doses may have a higher risk of kidney or nervous system effects.
Who should use Valtrex with caution?
People with kidney disease, dehydration, advanced age, weakened immune systems, or use of medicines that can affect the kidneys may need closer monitoring or dose adjustment. Anyone with a known allergy to valacyclovir or acyclovir should not use it.
Can Valtrex be used during pregnancy or breastfeeding?
Pregnant or breastfeeding people should discuss Valtrex use with a healthcare professional. Valacyclovir may be used in pregnancy or breastfeeding when the expected benefit is appropriate, but the decision depends on the infection being treated, medical history, and individual risk factors.
