Drug Interactions

Valacyclovir (Valtrex®) Interactions

Valacyclovir Drug Interactions

  • Probenecid, cimetidine: Decreased renal clearance of valacyclovir; no dosage adjustment needed in patients with normal renal function. [2]
  • Zoster Vaccine: valacyclovir may diminish the therapeutic effect of Zoster Vaccine. When possible, discontinue antiviral agent for at least 24 hours prior to and 14 days after receiving a live attenuated zoster vaccine.

Can you take Valacyclovir with Docosanol (Abreva®)?

Docosanol, the active ingredient in Abreva, is a fully saturated fatty alcohol. There are no any warnings regarding concomitant use of Abreva® and Valacyclovir.

Can you take Valacyclovir with Prednisone?

There are no interactions between prednisone and valacyclovir. The combination of valacyclovir and prednisone has been investigated in clinical trials in patients with Bell's palsy 3.

Can you take Valacyclovir with Isotretinoin (Accutane®)?

There are no reported interactions between Valacyclovir and retinoids.

Can you take Valacyclovir with birth control pills?

Valacyclovir does not interfere with the efficacy of birth control pills.

Can you take Valacyclovir and antibiotics at the same time?

You can safely take antibiotics while taking valacyclovir.

Valacyclovir during Pregnancy & Breastfeeding

Pregnancy Category: B. Valacyclovir is generally safe during pregnancy and breastfeeding. It was not teratogenic in rats or rabbits at 10 and 7 times human plasma levels, respectively, during the period of major organogenesis.

There are no adequate and well-controlled studies of Valtrex in pregnant women. A prospective epidemiologic study was established in 1984 and completed in April 1999. There were 749 pregnancies followed in women exposed to systemic acyclovir during the first trimester of pregnancy resulting in 756 outcomes. The occurrence of birth defects approximates that found in the general population.

Valacyclovir may be used during pregnancy or breastfeeding.

See also Can you take Valacyclovir and Acyclovir simultaneously?


  • 1. U.S. FDA. Valtrex Prescribing Information
  • 2. De Bony F, Tod M, Bidault R, On NT, Posner J, Rolan P. Multiple interactions of cimetidine and probenecid with valaciclovir and its metabolite. Antimicrob Agents Chemother. 2002 Feb;46(2):458-63. PubMedCentral
  • 3. Axelsson S, Lindberg S, Stjernquist-Desatnik A. Outcome of treatment with valacyclovir and prednisone in patients with Bell's palsy. Ann Otol Rhinol Laryngol. 2003 Mar;112(3):197-201. PubMed

By HealthyStock Research Group, September 2009
Medical resources reviewed: August 2018

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