Are there drug interactions between doxycycline (doxy) and acyclovir?

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Last updated: March 20, 2025View editorial policy

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From the Guidelines

Doxycycline and acyclovir can be used together without significant drug interactions, and no dose adjustments are typically required. When considering the use of doxycycline and acyclovir together, it's essential to understand their mechanisms of action and potential side effects. Doxycycline is an antibiotic that inhibits bacterial protein synthesis, while acyclovir is an antiviral medication that interferes with viral DNA replication, particularly for herpes viruses. Their different mechanisms of action and metabolic pathways mean they don't substantially interfere with each other's effectiveness or increase side effects 1. However, both medications can sometimes cause gastrointestinal side effects like nausea or stomach upset, so taking them with food (except for certain doxycycline formulations that require an empty stomach) may help minimize these effects. As with any medication combination, it's crucial to inform your healthcare provider about all medications you're taking to ensure your specific health conditions or other medications don't create unique interaction concerns. Additionally, the provided evidence does not suggest any significant interactions between doxycycline and acyclovir, and other studies support the safe use of these medications together 1. Some key points to consider when using these medications concurrently include:

  • Monitoring for potential gastrointestinal side effects
  • Informing your healthcare provider about all medications you're taking
  • Understanding the different mechanisms of action and metabolic pathways of doxycycline and acyclovir
  • Being aware of potential interactions with other medications you may be taking.

From the Research

Drug Interactions between Doxycycline and Acyclovir

There are no direct studies provided that investigate the drug interactions between doxycycline (doxy) and acyclovir.

Nephrotoxicity Associated with Acyclovir

  • Acyclovir can cause nephrotoxicity due to the accumulation of its crystals in renal tubules 2, 3, 4, 5.
  • Risk factors for acyclovir-induced nephrotoxicity include older age, concomitant use of nephrotoxic drugs, and higher doses of acyclovir 2, 3, 5.
  • Monitoring of kidney function is essential to prevent nephrotoxicity, especially in patients with risk factors 2, 4, 5.

Neurotoxicity Associated with Acyclovir

  • Acyclovir can also cause neurotoxicity, particularly in patients with impaired renal function or those using nephrotoxic drugs 6.
  • Neurotoxic side effects are reversible after therapy withdrawal, and early recognition can improve a patient's prognosis 6.

Lack of Direct Evidence

There are no research papers provided that directly investigate the interactions between doxycycline and acyclovir. The available studies focus on the nephrotoxicity and neurotoxicity associated with acyclovir use, but do not examine its interactions with doxycycline 2, 3, 4, 6, 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Incidence, patterns, risk factors and clinical outcomes of intravenous acyclovir induced nephrotoxicity.

Saudi pharmaceutical journal : SPJ : the official publication of the Saudi Pharmaceutical Society, 2022

Research

Clinical Review of Risk of Nephrotoxicity with Acyclovir Use for Treatment of Herpes Simplex Virus Infections in Neonates and Children.

The journal of pediatric pharmacology and therapeutics : JPPT : the official journal of PPAG, 2023

Research

Neurotoxic side effects of acyclovir: two case reports.

Neuro endocrinology letters, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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