Asthma Home > Zyflo Side Effects

Some common Zyflo side effects include indigestion or heartburn, nausea, and headaches. In most cases, side effects are minor and either don't require medical attention or can easily be treated. There are, however, a number of side effects with Zyflo that you should report to your healthcare provider immediately. Among these more serious side effects are worsening of asthma and signs of liver damage or an allergic reaction.

In February 2008, the manufacturer of Zyflo announced that it has discontinued making this product. The manufacturer stated that since the longer-acting version, Zyflo CR, became available in 2007, use of immediate-release Zyflo declined significantly. Zyflo CR will still be available.

An Introduction to Zyflo Side Effects

As with any medicine, there are possible side effects with Zyflo® (zileuton); however, not everyone who takes the medicine will experience side effects. In fact, most people tolerate Zyflo well. When side effects do occur, in most cases they are minor and either require no treatment or can easily be treated by you or your healthcare provider.
(This article covers many, but not all, of the possible side effects with Zyflo. Your healthcare provider can discuss a more complete list of Zyflo side effects with you.)

Common Side Effects With Zyflo

Zyflo has been studied thoroughly in clinical trials. In these studies, the side effects that occur in a group of people taking the drug are documented and are then compared to side effects that occur in another group of people not taking the drug. In these studies, the most common Zyflo side effects included:
  • Headaches -- in up to 24.6 percent of people
  • Indigestion or heartburn -- up to 8.2 percent
  • Pain -- up to 7.8 percent
  • Nausea -- up to 5.5 percent
  • Abdominal pain (or stomach pain) -- up to 4.6 percent
  • Weakness -- up to 3.8 percent
  • Accidental injury -- up to 3.4 percent
  • Muscle pain -- up to 3.2 percent.
Some other common side effects, occurring in 1 percent to 3 percent of people, included:
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Last reviewed by: Kristi Monson, PharmD;
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