Antiviral (nucleoside analogue)

Acyclovir: What to Know Before You Take It

Also sold as Zovirax

What Acyclovir Is Used For

INDICATIONS AND USAGE Herpes Zoster Infections : Acyclovir is indicated for the acute treatment of herpes zoster (shingles). Genital Herpes : Acyclovir is indicated for the treatment of initial episodes and the management of recurrent episodes of genital herpes. Chickenpox : Acyclovir is indicated for the treatment of chickenpox (varicella).

Warnings

WARNINGS Acyclovir capsules are intended for oral ingestion only. Renal failure, in some cases resulting in death, has been observed with acyclovir therapy (see ADVERSE REACTIONS: Observed During Clinical Practice and OVERDOSAGE ). Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), which has resulted in death, has occurred in immunocompromised patients receiving acyclovir therapy.

Contraindications

CONTRAINDICATIONS Acyclovir is contraindicated for patients who develop hypersensitivity to acyclovir or valacyclovir.

Acyclovir Drug Interactions (3)

Acyclovir + Valacyclovir

4 CONTRAINDICATIONS Valacyclovir tablets are contraindicated in patients who have had a demonstrated clinically significant hypersensitivity reaction [e.g., anaphylaxis, severe cutaneous adverse reactions (SCARs)] to valacyclovir, acyclovir, or any component of the formulation [see Warnings and Precautions (5.4) , Adverse Reactions (6.3) ] .

Contraindicated interaction

Acyclovir + Tizanidine

7.2 Moderate or Weak CYP1A2 Inhibitors Concomitant use of tizanidine with moderate or weak CYP1A2 inhibitors (e.g., zileuton, antiarrhythmics [amiodarone, mexiletine, propafenone, and verapamil], cimetidine, famotidine, oral contraceptives, acyclovir, and ticlopidine) should be avoided.

Major interaction

Acyclovir + Warfarin

Table 2: Examples of CYP450 Interactions with Warfarin Enzyme Inhibitors Inducers CYP2C9 amiodarone, capecitabine, cotrimoxazole, etravirine, fluconazole, fluvastatin, fluvoxamine, metronidazole, miconazole, oxandrolone, sulfinpyrazone, tigecycline, voriconazole, zafirlukast aprepitant, bosentan, carbamazepine, phenobarbital, rifampin CYP1A2 acyclovir, allopurinol, caffeine, cimetidine, ciprofloxacin, disulfiram, enoxacin, famotidine, fluvoxamine, methoxsalen, mexiletine, norfloxacin, oral co…

Minor interaction

Check Acyclovir against your full medication list in our free Interaction Checker

Most-Reported Side Effects

Based on 112,882 reports in the FDA Adverse Event Reporting System (FAERS). Reports do not prove the drug caused the effect.

fatigue7,859diarrhoea7,235off label use6,084pneumonia5,611nausea5,514pyrexia4,889death4,813drug ineffective4,656rash4,226dyspnoea3,585asthenia3,309headache3,210

Explore full Acyclovir safety data in our free FDA Safety Explorer

FDA Recalls (9)

Class IIOngoingDec 28, 2022

Presence of Particulate Matter: Customer complaint of dark particles found inside the vial

Recalling firm: Eugia US LLC

Class IICompletedSep 26, 2022

Presence of Particulate Matter: Customer complaint for a dark red, brown and black particulate floating inside vial.

Recalling firm: AuroMedics Pharma LLC

Class IIITerminatedApr 21, 2021

Labeling: Incorrect or Missing Lot and/or Exp Date

Recalling firm: Heritage Pharmaceuticals Inc

Class ITerminatedFeb 18, 2021

Crystallization: customer complaints for crystallization in finished product.

Recalling firm: Zydus Pharmaceuticals (USA) Inc

Class ITerminatedFeb 18, 2021

Crystallization: customer complaints for crystallization in finished product.

Recalling firm: Zydus Pharmaceuticals (USA) Inc

Class IITerminatedApr 25, 2019

Labeling; Label Mix-up; report received of one bottle labeled as Acyclovir Tablets USP 400 mg actually contained Carvedilol Tablets 6.25 mg

Recalling firm: Zydus Pharmaceuticals USA Inc

Class IITerminatedFeb 9, 2018

Presence of Foreign Tablet/Capsule; cartons labeled to contain Acyclovir tablets may contain Torsemide tablets in some of the blister cavities.

Recalling firm: Apace KY LLC

Class IIITerminatedApr 27, 2017

Presence of Foreign Substance: human hair melded into tablet.

Recalling firm: Hetero USA Inc

Class IITerminatedJul 17, 2013

Presence of Particulate Matter: Product from lot KF2199, may contain tablets with pieces of nitrile rubber glove embedded within the tablets.

Recalling firm: Apotex Inc.

This information is educational — not medical advice.

This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

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