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Japanese enceph vacc sa14-14-2, inactivated Side Effects

Medically reviewed by Last updated on Jun 12, 2023.

Applies to japanese enceph vacc sa14-14-2, inactivated: parenteral suspension for im use.

Side effects include:

Infants and children 2 months through 11 years of age: Fever, irritability, flu-like symptoms, diarrhea, vomiting, loss of appetite, rash, injection site reactions (pain, tenderness, erythema).

Adults and adolescents ≥12 years of age: Headache, myalgia, fatigue, influenza-like illness, nausea, injection site reactions (pain, tenderness, erythema, induration).

For Healthcare Professionals

Applies to japanese enceph vacc sa14-14-2, inactivated: intramuscular suspension.


The most common adverse events in adults were injection site reactions, headache, and myalgia. The most common adverse events in adolescents (12 to under 18 years) were injection site pain and tenderness. The most common adverse event in children (1 to under 12 years) was fever. The most common adverse events in infants (2 months to under 1 year) were injection site redness, fever, irritability, and diarrhea.[Ref]


Very common (10% or more): Redness (17.6%), pain (15%)

Common (1% to 10%): Tenderness, swelling, hardening, induration, edema, pruritus[Ref]


Very common (10% or more): Diarrhea (11.5%)

Common (1% to 10%): Vomiting, nausea

Frequency not reported: Rectal hemorrhage[Ref]


Very common (10% or more): Fever over 99.9F (23.7%), flu-like symptoms (13.3%), fatigue (11.3%)

Common (1% to 10%): Excessive fatigue

Frequency not reported: Chest pain, orthopedic injuries


Very common (10% or more): Myalgia (15.6%)

Common (1% to 10%): Back pain[Ref]

Nervous system

Common (1% to 10%): Headache

Frequency not reported: Febrile convulsions, multiple sclerosis

Postmarketing reports: Paresthesia, neuritis[Ref]

Febrile convulsions only occurred in patients under 3 years of age, onset was 2 days to over 5 months after vaccination with no apparent temporal clustering.

One case of multiple sclerosis was reported in adult clinical trials.[Ref]


Common (1% to 10%): Pharyngolaryngeal pain, cough[Ref]


Common (1% to 10%): Nasopharyngitis, rhinitis, upper respiratory tract infection

Frequency not reported: Appendicitis, limb abscess contralateral to injected arm


Common (1% to 10%): Rash

Frequency not reported: Dermatomyositis[Ref]


Frequency not reported: Disseminated intravascular coagulation

Disseminated intravascular coagulation after suspected bacterial meningitis leading to death occurred in a 12 year old male patient 4 months after the second dose of this vaccine.


Frequency not reported: Myocardial infarction

Myocardial infarction (MI) occurred in one adult patient with a history of MI, 3 weeks after receiving the second vaccine dose


Frequency not reported: Ovarian torsion


Common (1% to 10%): Loss of appetite


Very common (10% or more): Irritability (15.3%)


1. Product Information. Ixiaro (Japanese enceph vacc SA14-14-2, inactivated). Valneva USA. 2022.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.