Gardasil HPV Vaccine FAQ

Gardasil (Recombinant Human Papillomavirus Quadrivalent Vaccine)

Gardasil is a human papillomavirus (HPV) vaccine synthesized using recombinant technology. Gardasil is a sterile preparation for intramuscular injection and contains purified, inactive proteins from four types of HPV virus. It is noninfectious and contains viral-like particles (VLP) from HPV types 6, 11, 16, and 18. Gardasil 9 is effectve against cancer caused by Human Papillomavirus (HPV) types 16, 18, 31, 33, 45, 52, and 58 and genital warts (condyloma acuminata) caused by HPV types 6 and 11. Virus-like particles are structural virus proteins that resemble HPV virus. They can activate the immune system, but cannot replicate. Virus-like particles used in Gardasil are manufactured in yeast cells (S. cerevisiae) using recombinant technology. Once released from yeast cells, the VLPs are purified, combined with a catalyst (amorphous aluminum hydroxyphosphate sulfate) and a purification buffer. Gardasil-9 (9-valent HPV vaccine) will be the only HPV vaccine available in the U.S. after all lots of Gardasil (quadrivalent HPV vaccine) already distributed in the U.S. have expired.

Human papillomavirus causes cervical cancer, cervical adenocarcinoma, vaginal cancer and genital warts. Gardasil works by stimulating the immune system to attack HPV 6, 11, 16, and 18. Once Gardasil is administered, the body's immune system recognizes the viral proteins in Gardasil as foreign and develops antibodies against them, thus providing immunity to future infections. In the event of HPV exposure, the body will already be primed to fight the infection. HPV types 6, 11, 16, and 18 are commonly associated with HPV infections. HPV 16 and 18 cause 70% of cervical cancer and HPV 6 and 11 cause approximately 85% of genital warts.

In June 2006 the Food and Drug administration approved Gardasil for the prevention of HPV types 6, 11, 16, and 18 infections in girls and women aged 9-26 years. Gardasil is a quadrivalent vaccine, as it is effective against four types of HPV. The 9-valent version of Gardasil, Gardasil-9, protects against 9 types of HPV. Gardasil protects against cervical cancer (cancer of the lower end of the uterus or womb); abnormal and precancerous cervical lesions; abnormal and precancerous vaginal lesions; abnormal and precancerous vulvar lesions and genital warts. Gardasil does not treat HPV associated diseases.

How Effective Is Gardasil?

Girls should receive Gardasil before they are sexually active.  The Centers for Disease Control (CDC) recommends 11- to 12-year-olds get two doses of HPV vaccine, rather than the previously recommended three doses, to protect against cancers caused by HPV. The second dose should be given 6-12 months after the first dose. Three doses remain recommended for persons who initiate the vaccination series at ages 15 through 26 years and for immunocompromised people.

Gardasil was evaluated in 20,541 women 16-26 years of age prior to approval. Gardasil was effective in preventing nearly 100% of cervical cancers and a significant decrease in genital warts related to HPV 6, 11, 16, and 18. Gardasil does not protect against types of HPV not included in the vaccine and it does not treat HPV contracted prior to vaccination. Individuals who are already infected with one or more types of HPV included in Gardasil were protected from the remaining HPV types included in Gardasil following vaccination.

Precautions and Side Effects for Gardasil

The most common side effects of Gardasil are:

Patients should be observed for 15 minutes after injection because of fainting.

Allergic reactions, which may be severe, also occur.

Other side effects include:

  • swollen glands,
  • Guillain-Barré syndrome,
  • headache,
  • joint pain,
  • aching muscles, tiredness, or
  • weakness.

People allergic to any component in Gardasil should not use Gardasil. Gardasil does not treat active genital warts or cervical cancer. Individuals with a compromised immune system will not respond as well to Gardasil as individuals with a normal immune system.


Condoms are the best protection from sexually transmitted diseases (STDs). See Answer

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Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


"HPV Vaccine Information Statement"
Centers for Disease Control and Prevention