Name: Flublok

Cautions for Flublok


  • History of severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine.1 (See Sensitivity Reactions under Cautions.)


Sensitivity Reactions

Anaphylaxis, anaphylactoid reactions, allergic reactions, and other forms of hypersensitivity reported during postmarketing experience.1 100

Prior to administration, review patient’s history with respect to possible sensitivity reactions to the vaccine or vaccine components and prior vaccination-related adverse effects and assess benefits versus risks.100 112

Appropriate medical treatment and supervision must be available for immediate use in case an anaphylactic reaction occurs.1

Guillain-Barré Syndrome (GBS)

If GBS occurred within 6 weeks after previous influenza vaccination, manufacturer states base decision to administer influenza vaccine on careful consideration of potential benefits and risks.1

Unclear whether influenza vaccination increases risk of recurrence of GBS.100 Temporal association was noted between administration of 1976 swine influenza vaccine and GBS.1 100 Investigations to date suggest no large increase in GBS associated with influenza vaccine (other than 1976 swine influenza vaccine) and if influenza vaccine does pose a risk it probably is quite small (i.e., approximately 1 additional case of GBS per 1 million vaccinees).1 100

ACIP states that, as a precaution, individuals who are not at high risk for severe influenza complications and who developed GBS within 6 weeks of a previous dose of influenza vaccine generally should not receive influenza vaccination;100 clinicians might consider use of antiviral prophylaxis for such individuals.100 However, ACIP states that benefits of influenza vaccine may outweigh risks for certain individuals with a history of GBS who are at high risk for severe complications from influenza.100

Individuals with Altered Immunocompetence

May be administered to individuals immunosuppressed as the result of disease or immunosuppressive therapy.1 Consider possibility that immune response to the vaccine and efficacy may be reduced in these individuals.1

Limitations of Vaccine Effectiveness

Following seasonal influenza vaccination, up to 2 weeks may be required to develop antibody protection against infection.100

May not protect all vaccine recipients from influenza.1

Seasonal influenza vaccines are formulated annually to contain influenza A and B antigens predicted to represent strains of influenza virus likely to circulate in the US during the upcoming influenza season.1 100 567 Efficacy of seasonal vaccine during any given year depends on how closely viral strains represented in the vaccine match viral strains circulating during the season.100 166

Concomitant Illness

Delay administration in individuals with moderate to severe acute illness (with or without fever) until symptoms have subsided.134

ACIP states that mild diarrhea or mild upper respiratory tract illness or other acute illness (with or without fever) does not preclude vaccination.134

Individuals with Bleeding Disorders

Advise individuals who have bleeding disorders or are receiving anticoagulant therapy and/or their family members about the risk of hematoma from IM injections.134

ACIP states that vaccines may be given IM to such individuals if a clinician familiar with the patient's bleeding risk determines that the injection can be administered with reasonable safety.134 In these cases, use a fine needle (23 gauge or smaller) to administer the vaccine and apply firm pressure to the injection site (without rubbing) for ≥2 minutes.134 If patient is receiving antihemophilia therapy, administer the IM vaccine shortly after a scheduled dose of such therapy.134

Improper Storage and Handling

Improper storage or handling of vaccines may reduce vaccine potency resulting in reduced or inadequate immune response in vaccinees.134

Inspect all vaccines upon delivery and monitor during storage to ensure that the appropriate temperature is maintained.134 (See Storage under Stability.)

Do not administer vaccine that has been mishandled or has not been stored at the recommended temperature.134 If there are concerns about mishandling, contact the manufacturer or state or local immunization or health departments for guidance on whether the vaccine is usable.134

Specific Populations


Category B.1

Manufacturer states use in pregnant women only when clearly needed.1

Pregnancy registry at 888-855-7871.1 Clinicians or vaccinees should report any exposure to the vaccine that occurs during pregnancy.1


Not known whether influenza vaccine recombinant is distributed into milk.1 Manufacturer recommends caution.1

Pediatric Use

Safety and efficacy not established in children or adolescents <18 years of age.1

Some evidence that influenza vaccine recombinant may not be effective in children <3 years of age†.1

Geriatric Use

Some evidence that antibody responses are lower in adults ≥65 years of age compared with younger adults.1

Common Adverse Effects

Adults ≥18 years of age: Injection site reactions (e.g., pain), headache, fatigue, myalgia.1

Consumer Information Use and Disclaimer

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Check with your pharmacist about how to throw out unused drugs.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about Flublok, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about Flublok. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using Flublok.

Review Date: October 4, 2017

What happens if I overdose?

An overdose of Flublok is unlikely to occur.

For Healthcare Professionals

Applies to influenza virus vaccine, inactivated: intradermal suspension, intramuscular solution, intramuscular suspension, nasal spray


The most common adverse events were local reactions, myalgia, and headache.[Ref]


Very common (10% or more): Tenderness (89%), erythema/redness (76.4%), pain (73.8%), induration (58.4%), swelling (56.8%), injection-site pruritus (46.9%), itching (28%), bruising (18%), injection-site ecchymosis (14.9%), mass (11%)
Common (1% to 10%): Reaction, hemorrhage
Postmarketing reports: Cellulitis, injection site inflammation, injection site sterile abscess[Ref]


Very common (10% or more): Crying abnormal (41.2%), malaise (38%), fever (16%)
Common (1% to 10%): Chest tightness
Rare (less than 0.1%): Death
Postmarketing reports: Hot flashes/flushes[Ref]


Very common (10% or more): Myalgia (40%)
Common (1% to 10%): Chills/shivering, back pain
Postmarketing reports: Muscle weakness, arthritis, arthralgia, myasthenia[Ref]

Nervous system

Very common (10% or more): Headache (40%), drowsiness (37.7%), lethargy (14%)
Common (1% to 10%): Migraine
Postmarketing reports: Neuralgia, paresthesia, convulsions (including febrile seizures), encephalopathy, neuritis or neuropathy, transverse myelitis, Guillain-Barre syndrome, abnormal gait, dizziness, hypoesthesia, hypokinesia, tremor, somnolence, syncope, facial or cranial nerve paralysis, encephalopathy, limb paralysis, confusion, paralysis (including Bell's Palsy), vertigo, exacerbation of symptoms of mitochondrial encephalomyopathy (Leigh syndrome), meningitis, eosinophilic meningitis, vaccine-associated encephalitis[Ref]


Very common (10% or more): Runny nose/nasal congestion (58%), cough (15%), upper respiratory tract infection (13%)
Common (1% to 10%): Sore throat, cough, oropharyngeal pain, rhinorrhea, wheezing, pharyngolaryngeal pain, nasopharyngitis
Postmarketing reports: Rhinitis, laryngitis, dyspnea, dysphonia, bronchospasm, throat tightness, pharyngitis, epistaxis[Ref]


Very common (10% or more): Vomiting (15%), nausea (14.9%) diarrhea (13%)
Postmarketing reports: Dysphagia, abdominal pain, swelling of the mouth, throat, and/or tongue[Ref]


Very common (10% or more): Loss of appetite (33.3%), decreased appetite (21%)[Ref]


Very common (10% or more): Irritability (54%)
Postmarketing reports: Insomnia[Ref]


Postmarketing reports: Allergic reactions including anaphylactic shock, serum sickness, and death; Stevens-Johnson syndrome[Ref]


Common (1% to 10%): Infection, influenza-like illness
Postmarketing reports: Cellulitis[Ref]


Common (1% to 10%): Facial swelling
Postmarketing reports: Pruritus, urticaria, rash, angioedema, sweating, flushing, pallor, rash, erythema multiforme[Ref]


Common (1% to 10%): Reddened eyes
Postmarketing reports: Eye pain, photophobia, conjunctivitis, eye irritation, eye swelling, eyelid swelling, ocular hyperemia[Ref]


Postmarketing reports: Transient thrombocytopenia, lymphadenopathy[Ref]


Frequency not reported: Pleuropericarditis with effusions
Postmarketing reports: Tachycardia, pericarditis, vasculitis, vasodilation/flushing[Ref]


Postmarketing reports: Vasculitis with transient renal involvement[Ref]


Common (1% to 10%): Dysmenorrhea[Ref]

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