Most HPV vaccine side effects last one to three days. The most common reaction, soreness at the injection site, typically peaks within the first 24 hours and fades by day two or three. Systemic symptoms like headache, fatigue, and low-grade fever follow a similar timeline and rarely persist beyond 48 hours.
What Side Effects Are Most Common
Injection site pain is by far the most frequent side effect. In clinical trials of Gardasil 9, about 90% of recipients reported some degree of arm pain after at least one dose. For most people this was mild, with severe pain reported in only 4 to 6% of participants across all three doses. Swelling at the injection site occurred in roughly 40 to 48% of recipients, and redness in about 34%.
Systemic side effects are much less common. Fever of 100°F or higher occurred in about 6 to 7% of people after any dose, and only about 1% developed a fever above 102°F. Headache, fatigue, muscle pain, joint pain, nausea, and dizziness can also occur but are generally mild.
Timeline for Each Type of Side Effect
Clinical trials tracked side effects within a five-day window after each dose, and the vast majority of reactions appeared and resolved within that period. Here’s what to expect for the most common ones:
- Arm soreness: Begins within hours of the shot and usually resolves in one to two days. It may feel worse with the second or third dose.
- Swelling and redness: These tend to increase slightly with each successive dose and can take two to three days to fully clear.
- Headache and fatigue: Typically appear within the first day and resolve within 24 to 48 hours.
- Fever: Usually low-grade and short-lived, lasting less than a day. A fever that persists beyond one day is worth reporting to your doctor.
Why Side Effects Can Vary by Dose
You may notice that the second or third shot produces more soreness or swelling than the first. This is a normal immune response. In clinical trial data, swelling after the third dose was roughly double the rate seen after the first dose (28 to 36% versus 12 to 14%). Severe swelling also increased modestly with later doses. The duration of these reactions stays about the same, though. Even when swelling is more noticeable after a later dose, it still clears within a few days.
Fainting After the Shot
Fainting is a known concern with the HPV vaccine, but it’s related to the vaccination process itself, not the vaccine’s ingredients. The same reaction occurs at similar rates with other adolescent vaccines. It’s most likely to happen within 15 minutes of the injection, which is why you’ll be asked to sit in the clinic for a brief observation period afterward. This isn’t a lasting side effect. It’s a one-time vasovagal response (your body temporarily dropping blood pressure), and it resolves on its own within minutes.
Severe Allergic Reactions
Anaphylaxis, a serious allergic reaction, is extremely rare. The estimated rate is roughly 1.7 cases per million doses. When it does happen, it occurs within minutes of the injection, which is another reason for the 15-minute waiting period at the clinic. Signs include sudden hives over the body, swelling of the throat or tongue, difficulty breathing, and feeling faint or confused. This requires emergency treatment but is not a delayed side effect that would show up days later.
Managing Side Effects at Home
For arm soreness, applying a cold pack wrapped in a thin cloth for 10 to 20 minutes at a time helps reduce swelling and pain. Over-the-counter pain relievers like acetaminophen or ibuprofen can address soreness, headache, or mild fever. Keeping the arm moving gently throughout the day can also prevent stiffness.
Contact your doctor if you develop a rash or hives, noticeable swelling beyond the injection site, itching, or nausea that feels out of proportion to what you’d expect. A fever lasting more than one day also warrants a call. These situations are uncommon, but they’re the clearest signals that your body’s response has gone beyond the typical range.
Long-Term Side Effects
Large-scale safety surveillance has consistently found no evidence of chronic or long-term side effects from the HPV vaccine. The side effects that do occur are short-lived and self-limiting, resolving well within the first week. If you’re experiencing symptoms that started after vaccination and have lasted longer than five to seven days, they’re worth discussing with a healthcare provider, but they’re unlikely to be caused by the vaccine itself.