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
- right upper stomach pain
- unusual tiredness or weakness
- yellow eyes or skin
- Attack, assault, or force
- attempts at killing oneself
- dry mouth
- fear or nervousness
- feeling sad or empty
- irregular heartbeats
- lack of appetite
- loss of interest or pleasure
- seeing, hearing, or feeling things that are not there
- shakiness in the legs, arms, hands, or feet
- shortness of breath
- 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
- pain or tenderness around the eyes and cheekbones
- stuffy or runny nose
- tightness of the chest or wheezing
- troubled breathing
- upset stomach
- Abdominal or stomach pain
- sore throat
For Healthcare Professionals
Applies to zileuton: oral tablet, oral tablet extended release
Nervous system side effects have included headache (up to 24.6%), dizziness (greater than 1%), and somnolence (greater than 1%).
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).
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 side effects have included upper respiratory tract infection (9%), sinusitis (6.5%), and pharyngolaryngeal pain (5%).
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 side effects have included myalgia (up to 7%), arthralgia (greater than 1%), hypertonia (greater than 1%), and neck pain/rigidity (greater than 1%).
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 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 side effects have included pruritus (greater than 1%) and rash (1% or greater).
Genitourinary side effects have included urinary tract infection and vaginitis in greater than 1% of patients.
Hypersensitivity side effects have included hypersensitivity (1% or greater).
Ocular side effects have included conjunctivitis (greater than 1%).
More Zyflo CR resources
- Zyflo CR Concise Consumer Information (Cerner Multum)
- Zyflo CR Prescribing Information (FDA)
- Zyflo CR Advanced Consumer (Micromedex) - Includes Dosage Information
- Zyflo CR extended-release tablets MedFacts Consumer Leaflet (Wolters Kluwer)
- Zileuton Professional Patient Advice (Wolters Kluwer)
- Zileuton Monograph (AHFS DI)
- zileuton MedFacts Consumer Leaflet (Wolters Kluwer)
- Zyflo Prescribing Information (FDA)
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