Gardasil's Safety Concern Might be Unfounded

Last updated: December 2009

Should you expose your young daughter to potential risks from a vaccine that protects against cervical cancer--a disease that she may get 20 to 40 years from now? That's the question millions of parents face as television ads push for girls to receive Gardasil, a vaccine that prevents infection from four types of human papilloma virus (HPV)—the most common sexually transmitted virus in the U.S. Those four types cause most cases of cervical cancer and genital warts.

The Food and Drug Administration (FDA) approved Gardasil in 2006 for girls and young women to prevent cervical cancer and genital warts caused by the HPV types in the vaccine. But recently, complaints have emerged about the marketing and cost of Gardasil, and some parents have raised concerns about its safety. A new report by the FDA and the Centers for Disease Control and Prevention (CDC) found that serious complications had occurred, although most side effects appear to be consistent with those of other vaccines. "Safety monitoring hasn't revealed any major problems to date," says Lauri Markowitz, M.D., a medical epidemiologist at the CDC. "We think the benefits of the vaccine outweigh the risks."

To help you weigh the risks and benefits of Gardasil, we review the evidence.

How effective is Gardasil?

Studies involving about 21,000 girls and women found that for those who were not infected with HPV at the time of vaccination, Gardasil was highly effective in preventing precancerous cell changes that often develop into cancer of the cervix, vagina, and vulva, and in preventing genital warts.

But, if a girl or woman is already infected with one of the HPV types in the vaccine, Gardasil will not treat the infection nor prevent disease from that type. Moreover, because the vaccine doesn't protect against all HPV infections, it won't prevent about 30 percent of cervical cancers and 10 percent of genital warts. That's why Pap smears are still essential for early detection of cervical cancer, which has no symptoms until it's advanced. Protection from the vaccine is expected to be long lasting, but the duration of immunity is not yet known.

Who should get the vaccine and when? Gardasil provides maximum benefit for girls and women before they're sexually active. It's recommended for 11- and 12-year-old girls, but it can be given to those as young as 9 and to women up to age 26. Young women who are already infected may still partially benefit from the vaccine because very few have been infected with all the HPV types that it targets.

How much does the vaccine cost? The three-dose series costs about $375 ($125 per shot), not including office or physician charges. Most large insurance plans cover recommended vaccines, although some plans may not. In addition, some states provide free or low-cost vaccines to people without coverage, so check with your state's health department.

What are the risks of the vaccine? Reports of side effects and complications following vaccination are collected by the Vaccine Adverse Event Reporting System (VAERS), which is managed by the FDA and the CDC. The reports are unconfirmed and not necessarily related to the vaccine. In a 2009 review of the data, the agencies reported that more than 23 million doses of Gardasil were distributed between 2006 and 2008, and 12,424 reports had been filed.

Most of those were not serious and involved pain and redness at the injection site, dizziness, nausea, headaches, and fainting. But 6 percent of the reports were serious, including:

  • Deaths. There was no common pattern to the 32 reported deaths that would suggest they were caused by the vaccine. In most of the cases that had medical documentation, the deaths were linked to other factors, such as diabetes, viral illness, illicit drug use, and heart failure.
  • Guillain-Barre Syndrome (GBS). This disorder causes muscle weakness and tingling that can progress to paralysis. In a subsequent analysis of VAERS data, the University of Medicine and Dentistry in New Jersey concluded that the rate of GBS was in line with that of the general population. But the fact that most cases occurred within six weeks after vaccination warrants careful monitoring.
  • Blood clots. In the cases that had sufficient information for medical review, most of the women had a risk of getting blood clots, some from taking birth control pills. A higher proportion of blood clots were seen with Gardasil compared with other vaccines, but the proportion wasn't greater than expected in young women with risk factors for clotting. Still, this finding needs further investigation.

What safety precautions can you take with Gardasil?

People with minor illnesses (for example, diarrhea or a mild upper respiratory tract infection) can get the vaccine, but those with moderate or severe illnesses should wait until they recover.

To prevent falls in case of fainting, the vaccine recipient should remain seated or lying down for 15 minutes after the injection while a health professional observes her.

Seek medical attention if you notice any unusual conditions after the vaccination, such as a high fever or behavior changes. Signs of a serious allergic reaction include difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness.

Pregnant women should not start the vaccine. Although it has not been thoroughly tested to determine if it's safe for the mother and unborn baby, and research is underway, according to the CDC. But receiving the vaccine when pregnant is not a reason to consider terminating the pregnancy. Women who are breast-feeding may safely get the vaccine.

Anyone who has ever had a life-threatening allergic reaction to yeast or any other vaccine component, or to a previous dose, should not get the vaccine. Inform your doctor of any severe allergies.

Pap smears are strongly recommended for vaccinated women. Current guidelines advise beginning screening three years after the first sexual intercourse but not later than age 21, with repeat screening annually or at least every three years.

Use in men. The Food and Drug Administration has approved the Gardasil vaccine for preventing genital warts in boys and men, from 9 through 26. Both cervical cancer and genital warts are caused by strains of the human papilloma virus, the most common sexually transmitted infection in the U.S. About two out of every 1,000 American men are diagnosed with genital warts each year.

The FDA said the new approval was based on a trial involving more than 4,000 boys and men, ages 16 to 26, that found that Gardasil was nearly 90 percent effective in preventing genital warts caused by two types of HPV. Other studies that looked at the immune response in boys ages 9 through 15 found that the vaccine would be just as effective in this younger age group.  The FDA has also said that Merck, which manufactures Gardasil, is conducting additional studies to gather further information about the safety and effectiveness in boys and men.

Bottom line. For young women and men, Gardasil is an inactivated (not live) vaccine that protects against cervical cancer and genital warts. After reviewing available information, the FDA and CDC continue to find it safe and effective. Our advice: Consider the vaccine after you've discussed its risks and benefits with your physician.

If you have an adverse reaction to the vaccine, ask your health-care provider to file a VAERS form. Or call VAERS yourself at 800 822 7967, or go to

This drug safety alert is made possible through a partnership between Consumer Reports Best Buy Drugs and the Research on Adverse Drug Events and Reports (RADAR) group, a pharmacovigilance group led by Charles Bennett, M.D. Ph.D. M.P.P.

These materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multi-state settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).

If you think you have experienced an adverse event with this drug or any drug, especially if it is of a serious nature, it is important to 1) tell your doctor immediately and 2) report the event to the Food and Drug Administration via the FDA's MedWatch Web site at or by calling 1-800-FDA-1088.

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