Ask the Experts: HPV (Human Papillomavirus): Vaccine Safety

Results (3)

In clinical trials of 9vHPV (Gardasil 9, Merck) involving more than 15,000 vaccine recipients, most adverse events were mild or moderate injection site-related pain, swelling, and redness. Up to 40% reported one of these injection site reactions after vaccination, and they were more common among females compared to males. Injection site reactions also were more likely following the second or third dose compared to the first dose. Fewer than 10% of recipients reported fever.

Last reviewed: March 2, 2024

No. Since 2006, well over 100 million doses of HPV vaccine have been administered in the United States. Among all reports to the Vaccine Adverse Event Reporting System (VAERS) following HPV vaccines, the most frequently reported symptoms overall were dizziness; fainting; headache; nausea; fever; and pain, redness, and swelling in the arm where the shot was given. Although deaths have been reported among vaccine recipients none has been conclusively shown to have been caused by the vaccine. Occurrences of rare conditions, such as Guillain-Barré Syndrome (GBS) have also been reported among vaccine recipients but there is no evidence that HPV vaccination increased the rate of GBS above what is normally expected in the population.

CDC, working with the FDA and other immunization partners, continues to monitor the safety of HPV vaccines. You can find complete information on this and other vaccine safety issues and at

Last reviewed: March 2, 2024

Nearly all vaccines have been reported to be associated with fainting (syncope). Post-vaccination syncope has been most frequently reported after three vaccines commonly given to adolescents (HPV, MenACWY, and Tdap). However, it is not known whether the vaccines are responsible for post-vaccination syncope or if the association with these vaccines simply reflects the fact that adolescents are generally more likely to experience syncope due to needle- and pain-related anxiety.

Syncope can cause serious injury. Falls that occur due to syncope after vaccination can be prevented by having the vaccinated person seated or lying down. The person should be observed for 15 minutes following vaccination. For additional information about vaccination-associated syncope, see’s clinical resource, Vaccination-Related Syncope: Information for Healthcare Personnel at

Last reviewed: March 2, 2024

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