Side effects of the influenza vaccine

Side effects after vaccination against influenza are relatively uncommon. But if people have side effects that are different from the ones we already know, it is important to report them.

If you are unsure about which side effects are already known, you can look in the Danish package leaflet on indlaegsseddel.dk under the name of the medicine you use. The package leaflet contains information about possible side effects. When you report new side effects, you help us ensure that the vaccine is efficient and safe. Please follow the link in the right-hand factbox to report a side effect.  

Common side effects after vaccination against influenza

• Local reactions at the injection site
• Redness, irritation from the injection
• Widespread allergic reactions in the form of rash, watery eyes and nettle rash

Rare side effects after vaccination against influenza

• Cramps
• Anaemia

Very rare side effects after vaccination against influenza

• Inflammation of the blood vessels
• Inflammation of the brain
• Paralysis (Guillain-Barré syndrome)

Side effects of antiviral medicines against influenza

Tamiflu®

Common side effects:

• In adults: vomiting, nausea and headache
• In children: nausea

Rare side effects:

• Hypersensitivity reactions
• Psychiatric disorders
• Cramps

Relenza®

Rare side effects:

• Acute narrowing of airways
• Transient decline in lung function
• Allergic reactions, such as rash and nettle rash
• Seizures
• Psychiatric disorders such as hallucinations
• Abnormal behaviour.