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Valacyclovir Side Effects

For the Consumer

Applies to valacyclovir: oral tablet

As well as its needed effects, valacyclovir may cause unwanted side effects that require medical attention.

Major Side Effects

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

Minor Side Effects

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

Very common (10% or more): Nausea (up to 16%)
Common (1% to 10%): Vomiting, constipation, anorexia, dyspepsia, dry mouth, flatulence
Frequency not reported: Tooth disorder
Postmarketing reports: Diarrhea[Ref]

Nervous system

Very common (10% or more): Headache (up to 16%)
Common (1% to 10%): Dizziness, somnolence
Frequency not reported: Migraine
Postmarketing reports: Seizures, tremors, ataxia, coma, dysarthria, encephalopathy[Ref]

Neurologic/psychiatric events, sometimes severe, have included confusion, agitation, convulsions, hallucinations, and coma have generally been reversible with discontinuation. These events have mostly been seen in patients with renal impairment or in patients receiving higher doses.[Ref]

Psychiatric

Neurologic/psychiatric events, sometimes severe, have included confusion, agitation, convulsions, hallucinations, and coma have generally been reversible with discontinuation. These events have mostly been seen in patients with renal impairment or in patients receiving higher doses.[Ref]

Common (1% to 10%): Depression, insomnia
Postmarketing reports: Aggressive behavior, agitation, confusion, mania, psychosis, auditory and visual hallucinations[Ref]

Renal

Uncommon (0.1% to 1%): Increased serum creatinine
Frequency not reported: Acute renal failure
Postmarketing reports: Renal failure, renal pain[Ref]

Hematologic

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 per day.[Ref]

Common (1% to 10%): Decreased neutrophil counts, decreased platelet counts
Uncommon (0.1% to 1%): Decreased hemoglobin
Frequency not reported: Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome
Postmarketing reports: Thrombocytopenia, aplastic anemia, leukocytoclastic vasculitis[Ref]

Hepatic

Common (1% to 10%): Abnormal ALT, elevated alkaline phosphatase, elevated AST
Postmarketing reports: Hepatitis[Ref]

Hypersensitivity

Postmarketing reports: Acute hypersensitivity reactions including anaphylaxis, angioedema, dyspnea, pruritus, rash, urticaria[Ref]

Dermatologic

Common (1% to 10%): Rash
Frequency not reported: Acne, pruritus
Postmarketing reports: Facial edema, erythema multiforme, photosensitivity, alopecia[Ref]

Cardiovascular

Postmarketing reports: Hypertension, tachycardia[Ref]

Ocular

Postmarketing reports: Visual abnormalities[Ref]

Respiratory

Common (1% to 10%): Nasopharyngitis, upper respiratory tract infection, rhinitis, pharyngitis
Uncommon (0.1% to 1%): Dyspnea
Frequency not reported: Sinusitis, bronchitis[Ref]

Musculoskeletal

Common (1% to 10%): Arthralgia
Uncommon (0.1% to 1%): Back pain[Ref]

Genitourinary

Frequency not reported: Dysmenorrhea, urinary tract infection[Ref]

Other

Common (1% to 10%): Fatigue, asthenia, fever, chills[Ref]

General

The most commonly reported adverse reactions have been headache, nausea, and abdominal pain.[Ref]

References

1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

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

3. Cerner Multum, Inc. "Australian Product Information." O 0

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

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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