Can a flu vaccine cause nasal congestion?

Can Your Nose Get Stuffy After a Flu Vaccine?

Yes, nasal congestion is a well-documented side effect of the intranasal live attenuated influenza vaccine (LAIV), but not of the standard injectable flu vaccine.

Type of Vaccine Matters

Injectable Influenza Vaccines (Standard Flu Shot)

• Injectable influenza vaccines do not cause nasal congestion as they contain inactivated (killed) virus particles that cannot replicate in the nasal passages 1.
• The most common side effects of injectable vaccines are limited to injection site reactions (pain, redness, swelling) and systemic symptoms like fever, malaise, and myalgias, but not nasal symptoms 1, 2.

Intranasal Live Attenuated Influenza Vaccine (FluMist)

• Nasal congestion is one of the most common side effects of LAIV, occurring in 20-78% of recipients 1.
• Runny nose (rhinorrhea) is reported in 28-78% of adult LAIV recipients and 20-75% of children 1.
• These nasal symptoms occur because LAIV contains live attenuated viruses that replicate in the nasopharynx to generate an immune response 1.
• Nasal symptoms are more common after the first dose and are typically self-limited 1.

Clinical Evidence for LAIV-Related Nasal Symptoms

In Adults

• In a large clinical trial of 2,548 healthy adults aged 18-49 years receiving LAIV, runny nose was reported in 44.5% compared to 27.1% in placebo recipients 1.
• A recent 2024 study in older adults (65-85 years) found nasal congestion in 35-51% of LAIV recipients 3.
• Rhinorrhea occurred in 38-43% of participants receiving intranasal vaccine 3.

In Children

• Among children aged 60-71 months, runny nose was reported in 48.1% of LAIV recipients versus 44.2% of placebo recipients 1.
• Postlicensure studies confirm that fever and stuffy nose are more common in LAIV recipients than in those receiving injectable vaccines, particularly after the first dose 1.

Important Clinical Considerations

Pre-existing Nasal Congestion

• If significant nasal congestion is already present before vaccination, LAIV administration should be deferred until the congestion resolves, as it may impede vaccine delivery to the nasopharyngeal mucosa 1, 4.
• An injectable vaccine should be used instead if vaccination cannot be delayed 1.

Distinguishing Vaccine Reaction from Coincidental Illness

• Nasal symptoms from LAIV typically begin within 7 days of vaccination and are self-limited 1.
• Respiratory illness occurring after vaccination may represent coincidental infection rather than vaccine reaction, particularly if symptoms are severe or prolonged 5, 2.
• The vaccine contains only attenuated viruses and cannot cause influenza infection 5, 2.

When Nasal Symptoms Are Concerning

• Mild nasal congestion and rhinorrhea after LAIV are expected and require no treatment beyond symptomatic management 1.
• Seek medical attention if nasal symptoms are accompanied by respiratory distress, high fever persisting beyond 2 days, or signs of severe illness 5, 2.

Bottom Line

Nasal stuffiness after flu vaccination occurs only with the intranasal live vaccine (FluMist), affecting 20-78% of recipients, and is a normal expected reaction to the vaccine replicating in the nasal passages 1, 3. The standard injectable flu shot does not cause nasal congestion 1, 2.