HALF MOON BAY, Calif. -- Patients taking the wrong medicine or combining medicines that have an unexpected outcome can have dangerous or even fatal results. A recent federal study looked at medication errors and what might be done to reduce the startling number of errors that occur every year.

51-year-old Andrea Hayes of Half Moon Bay has epilepsy. Her condition is well-controlled by prescription medicines, but put herself at serious risk when she once innocently took an over-the-counter antihistamine.

"Who knew? I had allergies, I thought not a big deal, my allergist said no problem go ahead and take these," explained Hayes. "All of a sudden I started having seizures."

Fortunately she was at home, not out driving.

KTVU discovered in the Bay Area alone, so-called home medication errors injure some 50,000 people each year, kill hundreds more and cost millions in added health care. That's according to a recent federal review of medical records.

Michael Negrete of the Pharmacy Foundation of California stated that home-medication errors are increasing and vastly under reported.

"34 Americans a day on average die at home because of a medication error," said Negrete. "Patients may not even understand that their health problems are due to a medication issue, They may think it's a worsening of a disease state, or they may be embarrassed."

In some cases, the patients may not want their pharmacists or doctors to get in trouble.

In documents obtained through the Freedom of Information Act, KTVU discovered California issues about two citations a day to pharmacies committing serious medication errors. Experts say it's a tiny fraction of the actual mistakes.

But dispensing medications is only one link in a chain of opportunity for human error.

Pharmacists say one of the big problems is when patients leave the counter with new medicines, they may not know exactly what it's for. Some people, particularly aging patients receiving medication for a variety of ailments, have difficulty keeping track which prescription is for which problem.

The State Board of Pharmacy proposes a solution. New legislation would mandate changes to labels on prescription drugs. The new standard could include the problem being treated in bold type on the label.

State Senator Ellen Corbett (D-San Leandro) says there are privacy concerns and her bill accounts for them. After all, labeling your medical condition on the bottle might be embarrassing.

Pharmacists say more information would help them trying to decipher doctor's handwriting. Some California health insurers are beginning to ask doctors to use electronic or e-prescriptions.

Some physicians complain the interface is cumbersome and limiting. The governor wants it statewide by next year.

Advocates say patients should know their rights. Patient should never decline a face-to-face pharmacist consultation, even if clerks might apply pressure.

Two new studies show speaking with a pharmacist significantly reduces errors. You can get a yearly "meds check up" with a pharmacist or doctor. Medication therapy management may be covered by individual insurance policies.