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Zyflo CR Side Effects

Generic Name: zileuton

Note: This document contains side effect information about zileuton. Some of the dosage forms listed on this page may not apply to the brand name Zyflo CR.

Some side effects of Zyflo CR may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to zileuton: oral tablet, oral tablet extended release

Along with its needed effects, zileuton (the active ingredient contained in Zyflo CR) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking zileuton:

Rare
  • Flu-like symptoms
  • itching
  • right upper stomach pain
  • unusual tiredness or weakness
  • yellow eyes or skin
Incidence not known
  • Attack, assault, or force
  • attempts at killing oneself
  • discouragement
  • dry mouth
  • fear or nervousness
  • feeling sad or empty
  • hyperventilation
  • irregular heartbeats
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • shakiness in the legs, arms, hands, or feet
  • shortness of breath
  • sleeplessness
  • tiredness
  • trembling or shaking of the hands or feet
  • trouble with concentrating
  • trouble with sleeping
  • unable to sleep

Some side effects of zileuton may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Cough
  • fever
  • headache
  • nausea
  • pain or tenderness around the eyes and cheekbones
  • stuffy or runny nose
  • tightness of the chest or wheezing
  • troubled breathing
  • upset stomach
Less common
  • Abdominal or stomach pain
  • sore throat
  • weakness

For Healthcare Professionals

Applies to zileuton: oral tablet, oral tablet extended release

Nervous system

Nervous system side effects have included headache (up to 24.6%), dizziness (greater than 1%), and somnolence (greater than 1%).

Gastrointestinal

Gastrointestinal side effects have included dyspepsia (up to 8.2%), nausea (up to 5.5%), diarrhea (up to 5%), abdominal pain (up to 4.6%), constipation (greater than 1%), flatulence (greater than 1%), upper abdominal pain (1% or greater), and vomiting (1% or greater).

Hepatic

In subset analyses, females over the age of 65 appeared to be at an increased risk for ALT elevations.

With continued zileuton (the active ingredient contained in Zyflo CR) therapy, 52% of patients with ALT elevations between 3 to 5 times ULN had ALT levels drop below 2 times ULN, while 34% continued to demonstrate rising levels to greater than or equal to 5 times ULN. In patients in whom zileuton was discontinued, ALT levels dropped below 2 times ULN in approximately one month.

Hepatic side effects have included elevated ALT (greater than or equal to 3 times ULN; up to 4.6%), hepatotoxicity (1% or greater), at least one case of symptomatic hepatitis with jaundice, and at least three cases of mild hyperbilirubinemia (less than 3 times ULN) in patients with transaminase elevations. Elevations of one or more hepatic function enzymes and bilirubin have been reported. Cases of severe hepatic injury (including death, life-threatening liver injury with recovery, symptomatic jaundice, hyperbilirubinemia, and elevations of ALT greater than 8 times ULN) have been reported during postmarketing experience with the immediate-release tablets.

Respiratory

Respiratory side effects have included upper respiratory tract infection (9%), sinusitis (6.5%), and pharyngolaryngeal pain (5%).

Other

Other side effects have included pain (unspecified; 7.8%), asthenia (3.8%), accidental injury (3.4%), chest pain (greater than 1%), fever (greater than 1%), and malaise (greater than 1%).

Musculoskeletal

Musculoskeletal side effects have included myalgia (up to 7%), arthralgia (greater than 1%), hypertonia (greater than 1%), and neck pain/rigidity (greater than 1%).

Hematologic

Most cases of low white blood cell count were either transient or reversed upon discontinuation of zileuton (the active ingredient contained in Zyflo CR)

Hematologic side effects have included lymphadenopathy (greater than 1%) and low white blood cell count [less than 3 x 10(9)/L: 2.6%; less than or equal to 2.8 x 10(9)/L: 1%].

Psychiatric

Psychiatric side effects have included insomnia and nervousness in greater than 1% of patients. Sleep disorders and behavior changes have been reported during postmarketing experience.

Dermatologic

Dermatologic side effects have included pruritus (greater than 1%) and rash (1% or greater).

Genitourinary

Genitourinary side effects have included urinary tract infection and vaginitis in greater than 1% of patients.

Hypersensitivity

Hypersensitivity side effects have included hypersensitivity (1% or greater).

Ocular

Ocular side effects have included conjunctivitis (greater than 1%).

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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