Most side effects from the RSV vaccine are mild and resolve within one to three days. In clinical trials across all three approved RSV vaccines, the median duration of both local reactions (like injection site pain) and body-wide symptoms (like fatigue and headache) was one to two days. A small number of people experience effects that linger up to four days, but anything lasting beyond a week is uncommon.
What Side Effects to Expect
The most common reaction is soreness at the injection site. In trials for Arexvy (the GSK vaccine), about 61% of recipients reported injection site pain, compared to roughly 11% of those in the Abrysvo (Pfizer) trials for adults 60 and older. The difference largely reflects how the two vaccines are formulated, but in both cases the pain was overwhelmingly mild and short-lived.
Beyond the sore arm, the side effects you’re most likely to notice are fatigue, muscle aches, and headache. In Arexvy trials, fatigue affected about 34% of recipients, muscle pain about 29%, and headache about 27%. Redness and swelling at the injection site are less common, showing up in roughly 2% to 7% of people depending on the vaccine. mResvia, the newer mRNA-based vaccine from Moderna, carries a similar profile: soreness, redness, fatigue, headache, and muscle or joint pain.
How Long Each Type of Reaction Lasts
Side effects fall into two categories, and both clear up on a similar timeline.
Local reactions, meaning anything happening at or near the injection site, had a median duration of two days in Arexvy trials. Some people saw redness or swelling persist up to four days, but that was the upper range. For Abrysvo recipients 60 and older, the median was one to two days.
Systemic reactions, the whole-body symptoms like fatigue, headache, and muscle aches, also had a median duration of one to two days across both vaccines. Post-marketing surveillance data from the CDC confirms this pattern held up in the real world: the median time from vaccination to adverse event onset was just one day, and symptoms followed the same mild, brief course seen in the clinical trials.
Side Effects During Pregnancy
Abrysvo is the RSV vaccine approved for use during pregnancy (given between 32 and 36 weeks of gestation) to protect newborns. The side effect profile is slightly different from what older adults experience. About 41% of pregnant recipients reported injection site pain, with the vast majority describing it as mild. Redness appeared in about 7% and swelling in about 6%.
The majority of local and systemic reactions in pregnant participants resolved within two to three days of onset. CDC surveillance of the vaccine in pregnant people from August 2023 through May 2024 found that very few recipients sought medical care for their symptoms, and the pattern of reported reactions matched what was seen in the pre-approval trials.
Managing Discomfort at Home
There’s nothing unusual about managing RSV vaccine side effects. A cool cloth on the injection site can ease soreness and swelling. Staying hydrated and resting helps with fatigue and headache. Over-the-counter pain relievers like acetaminophen or ibuprofen can take the edge off if symptoms are bothersome, though most people find the discomfort mild enough to get through without them.
If your symptoms haven’t started improving after three or four days, or if they seem to be getting worse rather than better, that’s worth a call to your healthcare provider. Signs of a severe allergic reaction, which would typically appear within minutes to hours of vaccination, include hives, swelling of the face and throat, difficulty breathing, rapid heartbeat, and dizziness. These are rare but require immediate emergency care.
The Rare but Serious Risk: Guillain-Barré Syndrome
In 2024, the FDA added a warning to both Arexvy and Abrysvo after post-marketing data suggested a small increased risk of Guillain-Barré syndrome (GBS), a condition where the immune system attacks the nerves, causing weakness and sometimes temporary paralysis. The risk window is the 42 days following vaccination.
The numbers are very small. Among adults 65 and older, the estimated excess risk was about 9 cases per million doses for Abrysvo and 7 cases per million doses for Arexvy. To put that in perspective, that means for every million people vaccinated, between 7 and 9 additional GBS cases occurred beyond what would normally be expected. GBS symptoms typically start as tingling or weakness in the legs that can spread upward. If you notice progressive weakness in your limbs in the weeks following vaccination, seek medical attention promptly.