What are common medications that interact with acyclovir?

What other medications should be avoided while taking acyclovir?

Acyclovir is mainly excreted by the kidneys, so drugs that affect renal function or compete for active tubular secretion can raise its levels in the blood. Tizanidine increases acyclovir plasma concentration by 50-75 percent through this mechanism [1]. Tizanidine and acyclovir together also risk severe hypotension and sedation. Patients who take tizanidine regularly for muscle spasms should ask their doctor about switching to an alternative muscle relaxant.

What happens if acyclovir is taken with probenecid?

Probenecid blocks tubular secretion of acyclovir, reducing its elimination rate. This dopes up its plasma levels and prolongs its effect. The manufacturer recommends dose adjustment or careful monitoring when both drugs are used together [2]. Similar interactions occur with other organic anion transporter inhibitors such as methotrexate and nonsteroidal anti-inflammatory drugs.

Can acyclovir raise the risk of kidney damage when combined with other drugs?

Acyclovir itself is known to cause crystal-induced nephropathy. Drugs that reduce renal perfusion or promote dehydration amplify this risk. Cidofovir, amphotericin B, aminoglycosides, and foscarnet each increase kidney-injury probability. Patients with baseline renal impairment should receive hydration protocols and frequent creatinine checks.

Why do some people report higher side effects from acyclovir?

Higher plasma levels produced by renal tubular secretion blockers or impaired kidney function erklären why some patients see more neurotoxicity and nephrotoxicity. Neurotoxicity symptoms include tremor, confusion, and hallucination. The company recommends slow IV infusion rates and hydrated patients to limit this.

How long does the interaction last after stopping a competing drug?

Once a competing tubular secretion drug is stops, acyclovir plasma levels fall within one to two days depending on the competing product's half-life. For example, when tizanidine is stopped, acyclovir levels normalise within 2-3 days.