Relenza Side Effects

Generic Name: zanamivir

Please note - some side effects for Relenza may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Side Effects of Relenza - for the Consumer

Relenza

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Relenza:

Cough; diarrhea; dizziness; headache; nausea; sinus inflammation; sore throat; stuffy nose; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur when using Relenza:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, throat, or tongue); abnormal behavior; confusion; hallucinations; irregular heartbeat; mood or mental changes; rash with fever, mouth sores, or red and irritated eyes; red, swollen, blistered, or peeling skin; seizures; shortness of breath; symptoms of infection (eg, fever, chills, persistent sore throat); trouble swallowing; wheezing.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

Top

Relenza Side Effects - for the Professional

Relenza

See Warnings and Precautions for information about risk of serious adverse events such as bronchospasm (5.1) and allergic-like reactions (5.2), and for safety information in patients with underlying airways disease (5.1).

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The placebo used in clinical studies consisted of inhaled lactose powder, which is also the vehicle for the active drug; therefore, some adverse events occurring at similar frequencies in different treatment groups could be related to lactose vehicle inhalation.

Treatment of Influenza: Clinical Trials in Adults and Adolescents: Adverse events that occurred with an incidence ≥1.5% in treatment studies are listed in Table 1. This table shows adverse events occurring in patients aged ≥12 years receiving Relenza 10 mg inhaled twice daily, Relenza in all inhalation regimens, and placebo inhaled twice daily (where placebo consisted of the same lactose vehicle used in Relenza).

Table 1. Summary of Adverse Events ≥1.5% Incidence During Treatment in Adults and Adolescents

Adverse Event	Relenza		Placebo (Lactose Vehicle) (n = 1,520)
	10 mg b.i.d. Inhaled (n = 1,132)	All Dosing Regimensa (n = 2,289)
Body as a whole
Headaches	2%	2%	3%
Digestive
Diarrhea	3%	3%	4%
Nausea	3%	3%	3%
Vomiting	1%	1%	2%
Respiratory
Nasal signs and symptoms	2%	3%	3%
Bronchitis	2%	2%	3%
Cough	2%	2%	3%
Sinusitis	3%	2%	2%
Ear, nose, and throat infections	2%	1%	2%
Nervous system
Dizziness	2%	1%	<1%
a Includes studies where Relenza was administered intranasally (6.4 mg 2 to 4 times per day in addition to inhaled preparation) and/or inhaled more frequently (q.i.d.) than the currently recommended dose.

Additional adverse reactions occurring in less than 1.5% of patients receiving Relenza included malaise, fatigue, fever, abdominal pain, myalgia, arthralgia, and urticaria.

The most frequent laboratory abnormalities in Phase III treatment studies included elevations of liver enzymes and CPK, lymphopenia, and neutropenia. These were reported in similar proportions of zanamivir and lactose vehicle placebo recipients with acute influenza-like illness.

Clinical Trials in Pediatric Patients: Adverse events that occurred with an incidence ≥1.5% in children receiving treatment doses of Relenza in 2 Phase III studies are listed in Table 2. This table shows adverse events occurring in pediatric patients 5 to 12 years old receiving Relenza 10 mg inhaled twice daily and placebo inhaled twice daily (where placebo consisted of the same lactose vehicle used in Relenza).

Table 2. Summary of Adverse Events ≥1.5% Incidence During Treatment in Pediatric Patientsa

a Includes a subset of patients receiving Relenza for treatment of influenza in a prophylaxis study.
Adverse Event	Relenza 10 mg b.i.d. Inhaled (n = 291)	Placebo (Lactose Vehicle) (n = 318)
Respiratory
Ear, nose, and throat infections	5%	5%
Ear, nose, and throat hemorrhage	<1%	2%
Asthma	<1%	2%
Cough	<1%	2%
Digestive
Vomiting	2%	3%
Diarrhea	2%	2%
Nausea	<1%	2%

In 1 of the 2 studies described in Table 2, some additional information is available from children (5 to 12 years old) without acute influenza-like illness who received an investigational prophylaxis regimen of Relenza; 132 children received Relenza and 145 children received placebo. Among these children, nasal signs and symptoms (zanamivir 20%, placebo 9%), cough (zanamivir 16%, placebo 8%), and throat/tonsil discomfort and pain (zanamivir 11%, placebo 6%) were reported more frequently with Relenza than placebo. In a subset with chronic pulmonary disease, lower respiratory adverse events (described as asthma, cough, or viral respiratory infections which could include influenza-like symptoms) were reported in 7 of 7 zanamivir recipients and 5 of 12 placebo recipients.

Prophylaxis of Influenza: Family/Household Prophylaxis Studies: Adverse events that occurred with an incidence of ≥1.5% in the 2 prophylaxis studies are listed in Table 3. This table shows adverse events occurring in patients aged ≥5 years receiving Relenza 10 mg inhaled once daily for 10 days.

Table 3. Summary of Adverse Events ≥1.5% Incidence During 10-Day Prophylaxis Studies in Adults, Adolescents, and Childrena

a In prophylaxis studies, symptoms associated with influenza-like illness were captured as adverse events; subjects were enrolled during a winter respiratory season during which time any symptoms that occurred were captured as adverse events.
Adverse Event	Contact Cases
	Relenza (n = 1,068)	Placebo (n = 1,059)
Lower respiratory
Viral respiratory infections	13%	19%
Cough	7%	9%
Neurologic
Headaches	13%	14%
Ear, nose, and throat
Nasal signs and symptoms	12%	12%
Throat and tonsil discomfort and pain	8%	9%
Nasal inflammation	1%	2%
Musculoskeletal
Muscle pain	3%	3%
Endocrine and metabolic
Feeding problems (decreased or increased appetite and anorexia)	2%	2%
Gastrointestinal
Nausea and vomiting	1%	2%
Non-site specific
Malaise and fatigue	5%	5%
Temperature regulation disturbances (fever and/or chills)	5%	4%

Community Prophylaxis Studies: Adverse events that occurred with an incidence of ≥1.5% in 2 prophylaxis studies are listed in Table 4. This table shows adverse events occurring in patients aged ≥5 years receiving Relenza 10 mg inhaled once daily for 28 days.

Table 4. Summary of Adverse Events ≥1.5% Incidence During 28-Day Prophylaxis Studies in Adults, Adolescents, and Childrena

a In prophylaxis studies, symptoms associated with influenza-like illness were captured as adverse events; subjects were enrolled during a winter respiratory season during which time any symptoms that occurred were captured as adverse events.
Adverse Event	Relenza (n = 2,231)	Placebo (n = 2,239)
Neurologic
Headaches	24%	26%
Ear, nose, and throat
Throat and tonsil discomfort and pain	19%	20%
Nasal signs and symptoms	12%	13%
Ear, nose, and throat infections	2%	2%
Lower respiratory
Cough	17%	18%
Viral respiratory infections	3%	4%
Musculoskeletal
Muscle pain	8%	8%
Musculoskeletal pain	6%	6%
Arthralgia and articular rheumatism	2%	<1%
Endocrine and metabolic
Feeding problems (decreased or increased appetite and anorexia)	4%	4%
Gastrointestinal
Nausea and vomiting	2%	3%
Diarrhea	2%	2%
Non-site specific
Temperature regulation disturbances (fever and/or chills)	9%	10%
Malaise and fatigue	8%	8%

Postmarketing Experience

In addition to adverse events reported from clinical trials, the following events have been identified during postmarketing use of zanamivir (Relenza). Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to zanamivir (Relenza).

Allergic Reactions: Allergic or allergic-like reaction, including oropharyngeal edema [see Warnings and Precautions (5.2)].

Psychiatric: Delirium, including symptoms such as altered level of consciousness, confusion, abnormal behavior, delusions, hallucinations, agitation, anxiety, nightmares[see Warnings and Precautions (5.3)].

Cardiac: Arrhythmias, syncope.

Neurologic: Seizures. Vasovagal-like episodes have been reported shortly following inhalation of zanamivir.

Respiratory: Bronchospasm, dyspnea [see Warnings and Precautions (5.1)].

Skin: Facial edema; rash, including serious cutaneous reactions (e.g., erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis); urticaria [see Warnings and Precautions (5.2)].

Top

Side Effects by Body System - for Healthcare Professionals

General

Zanamivir is generally well-tolerated. In clinical trials, the incidence of adverse events in patients treated with zanamivir was similar to that in the placebo (lactose vehicle) group.

Respiratory

In a Phase I study, bronchospasm was reported in 1 of 13 patients with mild or moderate asthma following the administration of zanamivir. In a Phase III study of patients with acute influenza-like illness and underlying asthma or chronic obstructive pulmonary disease, more patients on zanamivir (10%) than on placebo (9%) experienced greater than 20% decline in FEV1 after 5 days of treatment.

Respiratory side effects have included cough (up to 17%), viral respiratory infections (up to 13%), nasal signs and symptoms (up to 12%), sinusitis (up to 3%), bronchitis (2%), ear, nose and throat infections (up to 2%), nasal inflammation (1%), decline in FEV1, congestion, rhinitis, and dry throat. Asthma, exacerbation of asthma, bronchospasm, respiratory arrest, dyspnea, lung tightness, and/or decline in lung function may occur in patients with underlying respiratory disease treated with zanamivir. Bronchospasm and dyspnea have been reported during postmarketing experience.

Nervous system

Nervous system side effects have included headache (up to 24%) and dizziness (up to 2%). Seizures, syncope, and vasovagal-like episodes shortly after inhalation have been reported during postmarketing experience.

Other

Other side effects have included throat and tonsil discomfort and pain (up to 19%), malaise (up to 8%), fatigue (up to 8%), temperature regulation disturbances (fever and/or chills; up to 9%), and abdominal pain in less than 1.5% of patients. Facial edema has been reported during postmarketing experience.

Musculoskeletal

Musculoskeletal side effects have included muscle pain (up to 8%), musculoskeletal pain (6%), arthralgia and articular rheumatism (up to 2%), and myalgia (less than 1.5%).

Dermatologic

Dermatologic side effects have included urticaria in less than 1.5% of patients. Rash, including serious cutaneous reactions (e.g., erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), and urticaria have been reported during postmarketing experience.

Hypersensitivity

Hypersensitivity side effects have included allergic or allergic-like reactions, including oropharyngeal edema, serious skin rashes, and anaphylaxis during postmarketing experience.

Psychiatric

Psychiatric side effects have included delirium, including symptoms such as altered level of consciousness, confusion, abnormal behavior, delusions, hallucinations, agitation, anxiety, nightmares, during postmarketing experience.

Abnormal behavior and delirium leading to injury, with fatal outcomes in some cases, with the use of zanamivir in influenza patients have been reported. Although frequency is unknown, based on zanamivir usage, these events appear to be uncommon. These events were primarily reported in pediatric patients and often had an abrupt onset and rapid resolution. Since influenza may be associated with neurologic and behavioral symptoms (including hallucinations, delirium, and abnormal behavior, with fatal outcomes in some cases), zanamivir's contribution to these events has not been established.

Gastrointestinal

Gastrointestinal side effects have included diarrhea (up to 3%), nausea (up to 3%), and vomiting (up to 2%).

Metabolic

Metabolic side effects have included feeding problems (decreased or increased appetite and anorexia; up to 4%) and elevated creatine phosphokinase.

Hepatic

Hepatic side effects have included elevated liver enzymes.

Hematologic

Hematologic side effects have included lymphopenia and neutropenia.

Cardiovascular

Cardiovascular side effects have included arrhythmias during postmarketing experience.

Renal

Renal side effects have included one case report acute renal failure, increased serum creatinine, hyperkalemia, and hypotension in a patient with multiple medical problems and multiple other medications.

Top

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 information does not endorse drugs, diagnose patients, or recommend therapy. This drug 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 drug combination in no way should be construed to indicate that the drug of drug combination is safe, effective, or appropriate for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of information 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 drugs you are taking, check with your doctor, nurse, or pharmacist.