evidence: HPV vaccines are very safe. Scientific research shows the benefits of HPV vaccination far outweigh the potential risks. Like all medical interventions, vaccines can have some side effects. More than 135 million doses of HPV vaccine have been distributed in the United States since the vaccine was introduced in 2006. The most common side effects associated with HPV vaccines are mild and include pain, redness, or swelling in the arm where the shot was given. [...] The HPV vaccine works extremely well. In the 10 years after the vaccine was recommended in 2006 in the United States, quadrivalent type HPV infections decreased by 86% in female teens aged 14 to 19 years and 71% in women in their early 20s. Research has also shown that fewer teens and young adults are getting genital warts and that cervical precancers are decreasing since HPV vaccines have been in use in the United States. Decreases in vaccine-type prevalence, genital warts, and cervical precancers have also been observed in other countries with HPV vaccination programs.