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Valtrex

Last reviewed on RxList: 3/22/2016
Valtrex Side Effects Center

Last reviewed on RxList 9/1/2016

Valtrex (valacyclovir) is an antiviral medication used to treat infections with:

Valtrex is available in generic form. Side effects of Valtrex include:

The dose of Valtrex depends on the condition being treated. Valtrex is taken as caplets that may be taken with or without food. Valtrex may interact with, lithium, methotrexate, pain or arthritis medicines, medicines used to treat ulcerative colitis, medicines used to prevent organ transplant rejection, IV antibiotics, antiviral medicines, or cancer medicines. Tell your doctor all medications and supplements you use. Valtrex showed no effects on the fetus in animal studies; however, there has been no adequate evaluation of Valtrex or (acyclovir) in pregnant women. Valtrex should only be used during pregnancy when the benefits to the mother outweigh risks to the fetus. The safety of Valtrex in breastfeeding infants has not been established. Methods other than breastfeeding should be considered if Valtrex must be taken while nursing.

Our Valtrex Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Valtrex Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop taking valacyclovir and call your doctor right away if you have any of the following signs of a serious side effect that can harm red blood cells:

  • fever, easy bruising or bleeding;
  • red spots on the skin (not related to herpes or chickenpox);
  • bloody diarrhea, vomiting;
  • pale or yellowed skin;
  • weakness or fainting; or
  • urinating less than usual or not at all.

Call your doctor at once if you have any of these other serious side effects:

  • pain in your lower back;
  • drowsiness, mood changes, increased thirst, loss of appetite, nausea and vomiting;
  • swelling, weight gain, feeling short of breath;
  • confusion, agitation, aggression, hallucinations, trouble concentrating;
  • feeling shaky or unsteady;
  • problems with speech or vision; or
  • seizure (convulsions).

Less serious side effects may include:

  • nausea, stomach pain;
  • headache, dizziness, tired feeling, depression;
  • joint pain;
  • menstrual pain;
  • mild skin rash; or
  • stuffy nose, sore throat.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Valtrex (Valacyclovir Hydrochloride)

Valtrex Professional Information

SIDE EFFECTS

The following serious adverse reactions are discussed in greater detail in other sections of the labeling:

The most common adverse reactions reported in at least 1 indication by greater than 10% of adult subjects treated with VALTREX and observed more frequently with VALTREX compared to placebo are headache, nausea, and abdominal pain. The only adverse reaction reported in greater than 10% of pediatric subjects aged less than 18 years was headache.

Clinical Trials Experience In Adult Subjects

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Cold Sores (Herpes Labialis)

In clinical trials for the treatment of cold sores, the adverse reactions reported by subjects receiving VALTREX 2 grams twice daily (n = 609) or placebo (n = 609) for 1 day, respectively, included headache (14%, 10%) and dizziness (2%, 1%). The frequencies of abnormal ALT (greater than 2 x ULN) were 1.8% for subjects receiving VALTREX compared with 0.8% for placebo. Other laboratory abnormalities (hemoglobin, white blood cells, alkaline phosphatase, and serum creatinine) occurred with similar frequencies in the 2 groups.

Genital Herpes

Initial Episode: In a clinical trial for the treatment of initial episodes of genital herpes, the adverse reactions reported by greater than or equal to 5% of subjects receiving VALTREX 1 gram twice daily for 10 days (n = 318) or oral acyclovir 200 mg 5 times daily for 10 days (n = 318), respectively, included headache (13%, 10%) and nausea (6%, 6%). For the incidence of laboratory abnormalities see Table 2.

Recurrent Episodes: In 3 clinical trials for the episodic treatment of recurrent genital herpes, the adverse reactions reported by greater than or equal to 5% of subjects receiving VALTREX 500 mg twice daily for 3 days (n = 402), VALTREX 500 mg twice daily for 5 days �(n = 1,136) or placebo (n = 259), respectively, included headache (16%, 11%, 14%) and nausea (5%, 4%, 5%). For the incidence of laboratory abnormalities see Table 2.

Suppressive Therapy: Suppression of Recurrent Genital Herpes in Immunocompetent Adults: In a clinical trial for the suppression of recurrent genital herpes infections, the adverse reactions reported by subjects receiving VALTREX 1 gram once daily (n = 269), VALTREX 500 mg once daily (n = 266), or placebo (n = 134), respectively, included headache (35%, 38%, 34%), nausea (11%, 11%, 8%), abdominal pain (11%, 9%, 6%), dysmenorrhea (8%, 5%, 4%), depression (7%, 5%, 5%), arthralgia (6%, 5%, 4%), vomiting (3%, 3%, 2%), and dizziness (4%, 2%, 1%). For the incidence of laboratory abnormalities see Table 2.

Suppression of Recurrent Genital Herpes in HIV-1-Infected Subjects: In HIV-1-infected subjects, frequently reported adverse reactions for VALTREX (500 mg twice daily; n = 194, median days on therapy = 172) and placebo (n = 99, median days on therapy = 59), respectively, included headache (13%, 8%), fatigue (8%, 5%), and rash (8%, 1%). Post-randomization laboratory abnormalities that were reported more frequently in valacyclovir subjects versus placebo included elevated alkaline phosphatase (4%, 2%), elevated ALT (14%, 10%), elevated AST (16%, 11%), decreased neutrophil counts (18%, 10%), and decreased platelet counts (3%, 0%), respectively.

Reduction of Transmission: In a clinical trial for the reduction of transmission of genital herpes, the adverse reactions reported by subjects receiving VALTREX 500 mg once daily (n = 743) or placebo once daily (n = 741), respectively, included headache (29%, 26%), nasopharyngitis (16%, 15%), and upper respiratory tract infection (9%, 10%).

Herpes Zoster

In 2 clinical trials for the treatment of herpes zoster, the adverse reactions reported by subjects receiving VALTREX 1 gram 3 times daily for 7 to 14 days (n = 967) or placebo (n = 195), respectively, included nausea (15%, 8%), headache (14%, 12%), vomiting (6%, 3%), dizziness (3%, 2%), and abdominal pain (3%, 2%). For the incidence of laboratory abnormalities see Table 2.

Table 2: Incidence (%) of Laboratory Abnormalities in Herpes Zoster and Genital Herpes Trial Populations

Laboratory Abnormality Herpes Zoster Genital Herpes Treatment Genital Herpes Suppression  
VALTREX 1 gram 3 Times Daily
(n = 967)
Placebo
(n = 195)
VALTREX 1 gram Twice Daily
(n = 1,194)
VALTREX 500 mg Twice Daily
(n = 1,159)
Placebo
(n = 439)
VALTREX 1 gram Once Daily
(n = 269)
VALTREX 500 mg Once Daily
(n = 266)
Placebo
(n = 134)
Hemoglobin ( < 0.8 x LLN) 0.8% 0% 0.3% 0.2% 0% 0% 0.8% 0.8%
White blood cells ( < 0.75 x LLN) 1.3% 0.6% 0.7% 0.6% 0.2% 0.7% 0.8% 1.5%
Platelet count ( < 100,000/mm³) 1.0% 1.2% 0.3% 0.1% 0.7% 0.4% 1.1% 1.5%
AST (SGOT) ( > 2 x ULN) 1.0% 0% 1.0% a 0.5% 4.1% 3.8% 3.0%
Serum creatinine ( > 1.5 x ULN) 0.2% 0% 0.7% 0% 0% 0% 0% 0%
a Data were not collected prospectively.
LLN = Lower limit of normal.
ULN = Upper limit of normal.

Clinical Trials Experience In Pediatric Subjects

The safety profile of VALTREX has been studied in 177 pediatric subjects aged 1 month to less than 18 years. Sixty-five of these pediatric subjects, aged 12 to less than 18 years, received oral caplets for 1 to 2 days for treatment of cold sores. The remaining 112 pediatric subjects, aged 1 month to less than 12 years, participated in 3 pharmacokinetic and safety trials and received valacyclovir oral suspension. Fifty-one of these 112 pediatric subjects received oral suspension for 3 to 6 days. The frequency, intensity, and nature of clinical adverse reactions and laboratory abnormalities were similar to those seen in adults.

Pediatric Subjects Aged 12 To Less Than 18 Years (Cold Sores)

In clinical trials for the treatment of cold sores, the adverse reactions reported by adolescent subjects receiving VALTREX 2 grams twice daily for 1 day, or VALTREX 2 grams twice daily for 1 day followed by 1 gram twice daily for 1 day (n = 65, across both dosing groups), or placebo (n = 30), respectively, included headache (17%, 3%) and nausea (8%, 0%).

Pediatric Subjects Aged 1 Month To Less Than 12 Years

Adverse events reported in more than 1 subject across the 3 pharmacokinetic and safety trials in children aged 1 month to less than 12 years were diarrhea (5%), pyrexia (4%), dehydration (2%), herpes simplex (2%), and rhinorrhea (2%). No clinically meaningful changes in laboratory values were observed.

Postmarketing Experience

In addition to adverse events reported from clinical trials, the following events have been identified during postmarketing use of VALTREX. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to VALTREX.

General: Facial edema, hypertension, tachycardia.

Allergic: Acute hypersensitivity reactions including anaphylaxis, angioedema, dyspnea, pruritus, rash, and urticaria [see CONTRAINDICATIONS].

CNS Symptoms: Aggressive behavior; agitation; ataxia; coma; confusion; decreased consciousness; dysarthria; encephalopathy; mania; and psychosis, including auditory and visual hallucinations, seizures, tremors [see WARNINGS AND PRECAUTIONS, Use In Specific Populations].

Eye: Visual abnormalities.

Gastrointestinal: Diarrhea.

Hepatobiliary Tract and Pancreas: Liver enzyme abnormalities, hepatitis.

Renal: Renal failure, renal pain (may be associated with renal failure) [see WARNINGS AND PRECAUTIONS, Use in Specific Populations].

Hematologic: Thrombocytopenia, aplastic anemia, leukocytoclastic vasculitis, TTP/HUS [see WARNINGS AND PRECAUTIONS].

Skin: Erythema multiforme, rashes including photosensitivity, alopecia.

Read the entire FDA prescribing information for Valtrex (Valacyclovir Hydrochloride)

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