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Valtrex Side Effects

Generic Name: valacyclovir

Note: This page contains side effects data for the generic drug valacyclovir. It is possible that some of the dosage forms included below may not apply to the brand name Valtrex.

It is possible that some side effects of Valtrex may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to valacyclovir: oral tablet

As well as its needed effects, valacyclovir (the active ingredient contained in Valtrex) may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking valacyclovir, check with your doctor immediately:

More common
  • Discouragement
  • feeling sad or empty
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • tiredness
  • trouble concentrating
  • trouble sleeping
Rare
  • Black, tarry stools
  • chest pain
  • chills
  • cough
  • decreased frequency or output of urine
  • fever
  • flu-like symptoms
  • headache
  • lower back or side pain
  • reduced mental alertness
  • shortness of breath
  • yellow eyes or skin
Incidence not known
  • Actions that are out of control
  • agitation
  • anxiety
  • back, leg, or stomach pains
  • bleeding gums
  • blood in urine or stools
  • blurred vision
  • change in consciousness
  • change in mental status
  • changes in behavior, especially in interactions with other people
  • changes in patterns and rhythms of speech
  • dark or bloody urine
  • difficult or labored breathing
  • difficulty speaking
  • difficulty swallowing
  • dizziness
  • drowsiness
  • dry mouth
  • fast, pounding, or irregular heartbeat or pulse
  • feeling that others are watching you or controlling your behavior
  • feeling that others can hear your thoughts
  • feeling, seeing, or hearing things that are not there
  • general tiredness and weakness
  • hyperventilation
  • increased thirst
  • itching
  • lightheadedness when getting up from a lying or sitting position
  • light-colored stools
  • loss of consciousness
  • mood or mental changes
  • nausea and vomiting
  • nervousness
  • pale color of skin
  • pinpoint red spots on the skin
  • pounding in the ears
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • redness of the skin
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • seizures
  • severe mood or mental changes
  • shakiness and unsteady walk
  • shakiness in the legs, arms, hands, or feet
  • skin rash
  • slurred speech
  • sores, ulcers, or white spots on the lips or in the mouth
  • stiff neck
  • swelling of the face, fingers, or lower legs
  • swollen or painful glands
  • talking, feeling, and acting with excitement
  • tightness in the chest
  • trembling or shaking of the hands or feet
  • trouble in speaking
  • troubled breathing
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual behavior
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • upper right abdominal pain
  • vomiting
  • weight gain
  • wheezing

Some valacyclovir side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common
  • Body aches or pain
  • cramps
  • difficulty in moving
  • ear congestion
  • heavy bleeding
  • loss of voice
  • muscle aches
  • muscle pain or stiffness
  • nasal congestion
  • pain
  • pain in joints
  • sneezing
  • sore throat
  • stuffy or runny nose
Less common
  • Constipation
  • diarrhea
Incidence not known
  • Blistering, peeling, or loosening of the skin
  • hair loss or thinning of the hair
  • hives or welts
  • increased sensitivity of skin to sunlight
  • red, irritated eyes
  • redness or other discoloration of the skin
  • severe sunburn

For Healthcare Professionals

Applies to valacyclovir: oral tablet

Gastrointestinal

Gastrointestinal side effects have included nausea (up to 15%), abdominal pain (up to 11%), and vomiting (up to 6%). Constipation, anorexia, diarrhea, elevated amylase, and elevated serum lipase have been reported. Diarrhea has been reported during postmarketing experience. In clinical trials of otherwise healthy individuals, frequencies were higher for patients over 50 years of age than for younger patients.[Ref]

Nervous system

Nervous system side effects have included headache (up to 38%) and dizziness (up to 4%). Central nervous system effects including agitation, seizures, and encephalopathy have been reported. Choreiform movements, myoclonus, vasculitic mononeuritis multiplex, somnolence, and Cotard's syndrome have been reported. Agitation, ataxia, coma, decreased consciousness, dysarthria, encephalopathy, seizures, and tremors have been reported during postmarketing experience. 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.[Ref]

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.[Ref]

Psychiatric

Psychiatric side effects have included depression (up to 7%) and disorientation. Central nervous system effects including hallucinations, confusion, and delirium have been reported. Aggressive behavior, confusion, mania, and psychosis (including auditory and visual hallucinations) have been reported during postmarketing experience.

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 (the active ingredient contained in Valtrex) 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.[Ref]

Renal side effects have included acute renal failure, elevated serum creatinine (up to 0.7%), renal toxicity, and renal failure (presenting as an increase in serum creatinine and blood urea nitrogen). Renal failure and renal pain (may be associated with renal failure) have been reported during postmarketing experience. 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.[Ref]

Hematologic

Hematologic side effects have included thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), and decreased neutrophil counts (18%), platelet counts (up to 3%), hemoglobin (up to 0.8%), and white blood cells (up to 1.3%). Thrombocytopenia, aplastic anemia, leukocytoclastic vasculitis, and TTP/HUS have been reported during postmarketing experience.[Ref]

TTP/HUS, including some fatalities, has been reported during clinical trials in patients with advanced HIV disease and in allogeneic bone marrow transplant and renal transplant recipients, who were receiving 8 g valacyclovir per day.[Ref]

Hepatic

Hepatic side effects have included elevated AST (up to 16%), ALT (up to 14%), and bilirubin. Liver enzyme abnormalities and hepatitis have been reported during postmarketing experience.[Ref]

Hypersensitivity

Hypersensitivity side effects have included acute hypersensitivity reactions (including anaphylaxis, angioedema, dyspnea, pruritus, rash, and urticaria) during postmarketing experience. Stevens-Johnson syndrome has been reported.[Ref]

Dermatologic

Dermatologic side effects have included rash (8%). Erythema multiforme, rashes including photosensitivity, and alopecia have been reported during postmarketing experience.[Ref]

Cardiovascular

Cardiovascular side effects have included hypertension and tachycardia during postmarketing experience.[Ref]

Ocular

Ocular side effects have included visual abnormalities during postmarketing experience.[Ref]

Respiratory

Respiratory side effects have included nasopharyngitis (16%) and upper respiratory tract infection (9%).[Ref]

Musculoskeletal

Musculoskeletal side effects have included arthralgia (up to 6%).[Ref]

Genitourinary

Genitourinary side effects have included dysmenorrhea (up to 8%).[Ref]

Other

Other side effects have included fatigue (8%). Facial edema has been reported during postmarketing experience.[Ref]

Metabolic

Metabolic side effects have included elevated alkaline phosphatase (4%) and hypoglycemia. At least one case of hypercalcemia has been reported.[Ref]

References

1. Hellden A, Odar-Cederlof I, Larsson K, Fehrman-Ekholm I, Linden T "Death delusion." BMJ 335 (2007): 1305

2. Abudalu M, Tyring S, Koltun W, Bodsworth N, Hamed K "Single-day, patient-initiated famciclovir therapy versus three-day valacyclovir regimen for recurrent genital herpes: a randomized, double-blind, comparative trial." Clin Infect Dis 47 (2008): 651-8

3. Fife KH, Warren TJ, Ferrera RD, et al. "Effect of valacyclovir on viral shedding in immunocompetent patients with recurrent herpes simplex virus 2 genital herpes: a US-based randomized, double-blind, placebo-controlled clinical trial." Mayo Clin Proc 81 (2006): 1321-7

4. Sheffield JS, Hill JB, Hollier LM, et al. "Valacyclovir prophylaxis to prevent recurrent herpes at delivery: a randomized clinical trial." Obstet Gynecol 108 (2006): 141-7

5. Wald A "New therapies and prevention strategies for genital herpes." Clin Infect Dis 28 (1999): s4-13

6. Beutner KR, Friedman DJ, Forszpaniak C, Andersen PL, Wood MJ "Valaciclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults." Antimicrob Agents Chemother 39 (1995): 1546-53

7. "Product Information. Valtrex (valacyclovir)." Glaxo Wellcome, Research Triangle Park, NC.

8. Dworkin RH, Johnson RW, Breuer J, et al. "Recommendations for the management of herpes zoster." Clin Infect Dis 44 Suppl 1 (2007): S1-S26

9. Feldman S, Rodman J, Gregory B "Excessive serum concentrations of acyclovir and neurotoxicity." J Infect Dis 157 (1988): 385-8

10. Pary LF, Henszel A, Kelkar P "Vasculitic mononeuritis multiplex induced by valacyclovir." Neurology 62 (2004): 1906-7

11. Wade JC, Meyers JD "Neurologic symptoms associated with parenteral acyclovir treatment after marrow transplantation." Ann Intern Med 98 (1983): 921-5

12. Jones PG, Beier-Hanratty SA "Acyclovir: neurologic and renal toxicity." Ann Intern Med 104 (1986): 892

13. Rivkin AM "Valacyclovir-induced seizures in end-stage renal disease." Ann Pharmacother 37 (2003): 1913

14. Okada T, Nakao T, Matsumoto H, et al. "Valacyclovir neurotoxicity in a patient with end-stage renal disease treated with continuous ambulatory peritoneal dialysis." Clin Nephrol 58 (2002): 168-70

15. Cohen SM, Minkove JA, Zebley JW, Mulholland JH "Severe but reversible neurotoxicity from acyclovir." Ann Intern Med 100 (1984): 920

16. Kimberlin DF, Weller S, Whitley R, Andrews WW, Hauth JC, Lakeman F, Miller G "Pharmacokinetics of oral valacyclovir and acyclovir in late pregnancy." Am J Obstet Gynecol 179 (1998): 846-51

17. Becker BN, Fall P, Hall C, Milam D, Leonard J, Glick A, Schulman G "Rapidly progressive acute renal failure due to acyclovir: case report and review of the literature." Am J Kidney Dis 22 (1993): 611-5

18. Slifkin M, Doron S, Snydman DR "Viral prophylaxis in organ transplant patients." Drugs 64 (2004): 2763-92

19. Bean B, Aeppli D "Adverse effects of high-dose intravenous acyclovir in ambulatory patients with acute herpes zoster." J Infect Dis 151 (1985): 362-5

20. Reischig T, Jindra P, Mares J, et al. "Valacyclovir for Cytomegalovirus Prophylaxis Reduces the Risk of Acute Renal Allograft Rejection." Transplantation 79 (2005): 317-324

21. Tomson CR, Goodship TH, Rodger RS "Psychiatric side-effects of acyclovir in patients with chronic renal failure." Lancet 2 (1985): 385-6

22. Rashiq S, Briewa L, Mooney M, Giancarlo T, Khatib R, Wilson FM "Distinguishing acyclovir neurotoxicity from encephalomyelitis." J Intern Med 234 (1993): 507-11

23. LinssenSchuurmans CD, vanKan EJM, Feith GW, Uges DRA "Neurotoxicity caused by valacyclovir in a patient on hemodialysis." Ther Drug Monit 20 (1998): 385-6

24. Gill MJ, Burgess E "Neurotoxicity of acyclovir in end stage renal disease." J Antimicrob Chemother 25 (1990): 300-1

25. MacDiarmaid-Gordon AR, O'Connor M, Beaman M, Ackrill P "Neurotoxicity associated with oral acyclovir in patients undergoing dialysis." Nephron 62 (1992): 280-3

26. Maru MC, Fialkow RZ, Haria DM "Choreiform movements in dialysis patient taking valacyclovir and famciclovir." South Med J 94 (2001): 655

27. Fletcher CV, Chinnock BJ, Chace B, Balfour HH "Pharmacokinetics and safety of high-dose oral acyclovir for suppression of cytomegalovirus disease after renal transplantation." Clin Pharmacol Ther 44 (1988): 158-63

28. Krieble BF, Rudy DW, Glick MR, Clayman MD "Case report: acyclovir neurotoxicity and nephrotoxicity--the role for hemodialysis." Am J Med Sci 305 (1993): 36-9

29. O'Brien JJ, Campoli-Richards DM "Acyclovir: an updated review of its antiviral activity, pharmacokinetic properties and therapeutic efficacy." Drugs 37 (1989): 233-309

30. Beales P, Almond MK, Kwan JTC "Acyclovir neurotoxicity following oral therapy - prevention and treatment in patients on haemodialysis." Nephron 66 (1994): 362-3

31. Mataix AL, Duarte J, Revuelta K, et al. "Oral acyclovir and neurologic adverse effects in endstage renal disease." Ann Pharmacother 28 (1991): 961-2

32. Rashed A, Asadeh B, Romeh SHA "Acyclovir-induced acute tubulo-interstitial nephritis." Nephron 56 (1990): 436-8

33. Sawyer MH, Webb DE, Balow JE, Straus SE "Acyclovir-induced renal failure." Am J Med 84 (1988): 1067-71

34. Izzedine H, Launay-Vacher V, Deray G "Antiviral drug-induced nephrotoxicity." Am J Kidney Dis 45 (2005): 804-17

35. Roberts DM, Smith MW, McMullan BJ, Sevastos J, Day RO "Acute kidney injury due to crystalluria following acute valacyclovir overdose." Kidney Int 79 (2011): 574

36. Hernandez E, Praga M, Moreno F, Montoyo C "Acute renal failure induced by oral acyclovir." Clin Nephrol 36 (1991): 155-6

37. Gnann JW, Barton NH, Whitley RJ "Acyclovir: mechanism of action, pharmacokinetics, safety and clinical applications." Pharmacotherapy 3 (1983): 275-83

38. Peterslund NA, Larsen ML, Mygind H "Acyclovir crystalluria." Scand J Infect Dis 20 (1988): 225-8

39. Bianchetti MG, Roduit C, Oetliker OH "Acyclovir-induced renal failure: course and risk factors." Pediatr Nephrol 5 (1991): 238-9

40. Rivaud E, Massiani MA, Vincent F, Azoulay E, Couderc LJ "Valacyclovir hydrochloride therapy and thrombotic thrombocytopenic purpura in a HIV-infected patient." Arch Intern Med 160 (2000): 1705-6

41. Jacobson MA, Gallant J, Wang LH, Coakley D, Weller S, Gary D, Squires L, Smiley ML, Blum MR, Feinberg J "Phase I trial of valaciclovir, the L-valyl ester of acyclovir, in patients with advanced human immunodeficiency virus disease." Antimicrob Agents Chemother 38 (1994): 1534-40

42. Mindel A, Carney O. Freris M, Faherty A, Patou G, Williams P "Dosage and safety of long-term suppressive acyclovir therapy for recurrent genital herpes." Lancet Apr (1988): 926-8

43. Fazal BA, Turett GS, Justman JE, Hall G, Telzak EE "Stevens-johnson syndrome induced by treatment with acyclovir." Clin Infect Dis 21 (1995): 1038-9

44. Cheungpasitporn W, Suksaranjit P, Chanprasert S "Hypercalcemia in human immunodeficiency virus-related lymphoma and valacyclovir toxicity." Am J Med Sci 342 (2011): 539

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