A vaccine designed to protect young women is making some of them very sick.

We're talking about the Gardasil vaccine. Thousands of Wisconsin women have had the shots.

Gardasil is a vaccine that can prevent most cervical cancer in women, but occasionally severe side effects have some families terrified.

Ally Klann is a healthy, athletic 15-year-old. She's good in school, great at sports, and always on the go. Three weeks ago, everything came to an abrupt stop.

"I don't have words to explain how frightened I was and how scared I was for her," Ally’s mom, Joy Klann said.

Joy took Ally to a Menomonee Falls clinic for a routine physical. As part of that exam, Ally was offered the Gardasil vaccine. The vaccine targets strains of the human papillomavirus that are most likely to cause cervical cancer. Joy says she asked about side effects and was told only about possible redness and soreness.

Ally got the shot and almost immediately, something went very wrong.

"I stood up and couldn't see anything. I was like, 'Mom, it is supposed to be like this?' And then I don't remember anything from that," Ally said.

Ally’s mom said Ally fainted and began having seizure like motions. For several moments, Ally was thrashing on the examining room floor.

"I remember waking up and asking where I was because I really didn't know," Ally recalled. "They had me sit on the ground, and then eventually move up to sit on the table, and then I started feeling nauseous."

"When she came to she was very much out of it. Very pale. She didn't know where she was or who I was," Joy said. "I didn't know what was happening. It was the scariest thing I've ever seen."

Ally remembers her mom being shaken up.

"She probably was as pale as I was. She didn't look good,” Ally said.

After more than two hours, Ally was sent home. Her parents were afraid to let her sleep, and it took five days for Ally to get over the migraine-like headaches and debilitating loss of energy. When the Klahns went online to learn more about side effects they were shocked.

"We were shocked at some of the things we read," Ally’s dad, Keith Klann said.

The list of side effects stunned the Klahns: seizures, fainting, dizziness, severe nausea, increased blood pressure, chronic fatigue. The Centers for Disease Control tracks bad reactions to Gardasil and a report released late this spring found nearly 8,000 problems related to the shot.

The Klahn's call to the clinic to discuss that was a real eye opener.

"They weren't aware that there were any side effects and I was just shocked by that," Keith claims.

The clinic never returned our phone calls.

Dr. Wendi Ehrman specializes in Pediatrics at the Medical College of Wisconsin.

"We've given hundreds of shots here and I don't remember anybody that being a problem. Feeling faint? Yes, but I don't think we've had anybody pass out from it,” Dr. Ehrman said.

Dr. Ehrman believes the vaccine is a critical tool in the battle against cancer.

"This is one of only two vaccines we have that can actually prevent cancer. If we can do something at a young age to prevent cancer, cervical cancer, why not?" Dr. Ehrman said.

Ally is back on the softball field and feeling strong after a real scare and feeling strongly that doctors and nurses need to discuss the possible side effects with their patients.

"They better be telling these girls and the parents that that is a possible side effect. My body obviously had some reaction to it and didn't like it," Ally told us.

Each year 12,000 women in the are diagnosed with cervical cancer. Four thousand women die from it.

This vaccine can help lower those numbers. The problem is it's a relatively new drug. We don't know much about long-term side effects.