Valtrex Side Effects

Please note - some side effects for Valtrex may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Valtrex - for the Consumer

Valtrex

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Valtrex:

Dizziness; headache; nausea; stomach pain; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); aggressive behavior; bloody or dark urine; change in the amount of urine produced; confusion; depression; fatigue; fever; hallucinations; joint pain; lower back pain; pale skin; painful menstrual periods; pinpoint bruises; seizures; severe abdominal pain; shaky movements; speech problems; swelling of the face, hands, feet, or entire body; unsteady movement; unusual bruising or bleeding from the nose or mouth; weakness; yellowing of the skin or eyes.

Valtrex Side Effects - for the Professional

Valtrex

• The most common adverse reactions reported in at least one indication by >10% of adult patients treated with Valtrex and more commonly than in patients treated with placebo are headache, nausea, and abdominal pain. (6.1)
• The only adverse reaction occurring in >10% of pediatric patients <18 years of age was headache. (6.2)

  To report SUSPECTED ADVERSE REACTIONS, contact GlaxoSmithKline at 1-888-825-5249 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

   

  Revised: September 2008
  VTX:2PI

Side Effects by Body System

Gastrointestinal

Gastrointestinal disturbances are the most commonly reported adverse effects and include nausea (5% to 15%), vomiting (less than 1% to 6%), abdominal pain (1% to 11%), constipation (1% to 5%), anorexia (1% to 3%), and diarrhea (4% to 5%). Elevated amylase and serum lipase have also been reported. In clinical trials of otherwise healthy individuals, frequencies were higher for patients over 50 years of age than for younger patients.

Nervous system

Acyclovir neurotoxicity is almost exclusively seen in patients with renal failure. These patients may have longstanding chronic renal failure, or acute failure which may be attributed to acyclovir. One group of six bone marrow transplant patients exhibited abnormal EEGs with diffuse slowing. Although more commonly seen with intravenous administration of higher doses, neurotoxicity has also been reported in patients receiving oral doses of acyclovir. Following discontinuation of therapy, mental status recovered within about a week. Several patients with chronic renal failure exhibiting neurotoxicity improved dramatically following hemodialysis.

Although there have been no similar reports in clinical trials of valacyclovir completed to date, the assumption may be made that neurotoxicity can also occur with valacyclovir based on the fact that plasma acyclovir concentrations from oral valacyclovir administration tend to be much higher than those obtained with oral acyclovir.

Nervous system side effects have included headache (13% to 38%), dizziness (2% to 4%), depression (1% to 7%), aggressive behavior, agitation, ataxia, coma, confusion, disorientation, decreased consciousness, dysarthria, encephalopathy, mania, psychosis, auditory and visual hallucinations, seizures, choreiform movements, myoclonus, tremors, vasculitic mononeuritis multiplex, somnolence, and Cotard's syndrome. Neurotoxicity has been most commonly reported in patients with renal failure, the elderly, and in patients following bone marrow transplant, and is associated with high serum concentrations of acyclovir.

Renal

Transient renal dysfunction has been reported with both oral and intravenous administration of acyclovir. Crystallization of the drug in the renal tubules is thought to be the mechanism for the development of renal dysfunction based on findings of crystalluria in several case reports and at least one prospective study. Inadequate hydration of the patient and rapid administration of the drug may contribute to the development of crystalluria. Acute tubular necrosis and interstitial nephritis have also been reported in association with acyclovir therapy. Although there have been no similar reports in clinical trials of valacyclovir completed to date, the assumption may be made that renal toxicity can also occur with valacyclovir based on the fact that plasma acyclovir concentrations from oral valacyclovir administration tend to be much higher than those obtained with oral acyclovir.

Renal side effects have included renal toxicity and renal failure, presenting as an increase in serum creatinine and blood urea nitrogen. Renal pain (may be associated with renal failure) has also been reported. Renal effects are transient and resolve over several days following discontinuation of therapy. Renal damage is most likely due to crystallization of acyclovir in the renal tubules. Patients with preexisting renal insufficiency are at greater risk for developing neurotoxicity and further deterioration in renal function.

Hematologic

Hematologic side effects have included thrombocytopenia, aplastic anemia, leukocytoclastic vasculitis, decreased hemoglobin, decreased white blood cells, decreased platelets, decreased neutrophils, and thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS).

Several cases of TTP/HUS have been reported in a study of valacyclovir for CMV suppression in end-stage AIDS patients. The syndrome has also been observed in bone marrow transplant and renal transplant patients in clinical trials of valacyclovir. No such cases have been reported in immunocompetent patients.

Hepatic

Hepatic side effects have included elevated AST, ALT, bilirubin, and alkaline phosphatase, and hepatitis.

Hypersensitivity

Hypersensitivity reactions have included anaphylaxis, angioedema, dyspnea, pruritus, rash, urticaria, and Stevens-Johnson syndrome.

Dermatologic

Dermatologic side effects have included erythema multiforme, rash, photosensitivity, and alopecia.

Cardiovascular

Cardiovascular side effects have included hypertension and tachycardia.

Ocular

Ocular side effects have included visual abnormalities.

Respiratory

Respiratory side effects have included nasopharyngitis and upper respiratory tract infection.

Musculoskeletal

Musculoskeletal side effects have included arthralgia (less than 1% to 6%).

Genitourinary

Genitourinary side effects have included dysmenorrhea (less than 1% to 8%).

Other

Other side effects have included facial edema and fatigue.

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