People are mixing supplements, herbs and over-the-counter medications and prescription drugs to cure themselves of ills, unaware that they could be making themselves sicker, says George Grossberg, M.D., director of the division of geriatric psychiatry at Saint Louis University.

Dr. Grossberg is about to change all that. He is the co-author of a new book, "The Essential Herb-Drug-Vitamin Interaction Guide," which is a comprehensive listing of what various herbs and supplements do, possible side effects and how they might interact with other medications and foods.

"People think if it doesn't require a prescription, it's got to be safe, and that's not true. There could be life-threatening effects."

Dr. Grossberg first became interested in the topic after a routine six-month visit with a patient he had successfully treated for depression. He had been seeing the patient for four or five years, and asked if the man was dealing with any new health problems.

The patient mentioned that he was scheduled to go in for cystoscopy in a couple weeks because there had been blood in his urine. The procedure involves inserting the pencil-thin tip of a probe through the urethra, up to the bladder to detect the cause of the problem.

The patient had undergone thousands of dollars of MRIs and CAT scans of his lower abdomen and pelvis, which had not revealed the reason for the bleeding, and the test was the next diagnostic step.

Dr. Grossberg asked if the patient had changed anything – perhaps had started taking a new medication.

No new medicine. Then the patient's wife pulled from her purse a vial containing a supplement she had purchased from the health food store to enhance memory. Both husband and wife had started taking the herbal memory enhancer, which largely contained ginkgo biloba

"One of the side effects of ginkgo biloba is an increased risk of bleeding. He had no awareness of this. I told him to stop taking the herb and get rechecked before having cystoscopy. The bleeding stopped, and he didn't need the test."

Dr. Grossberg ticks off other common herbs that people take without realizing their side effects or how they might interact with medications.

St. John's wort sometimes is taken for anxiety and depression. Those who also are taking antidepressants or anti-anxiety medications, such as Prozac, Zoloft or Paxil, should beware. Mixing St. John's wort with these medicines can cause serotonin syndrome -- with symptoms that may include agitation, rapid heart beat, flushing and heavy sweating -- that may be fatal.

Dong quai, which some women take for menstrual disorders and to ease symptoms of menopause, has been linked to cardiovascular problems, such as irregular heart rhythm and low blood pressure. If a patient takes the herb along with an antihypertensive drug, her blood pressure could plummet, putting her at risk of stroke.

Some people take echinacea, which enhances the immune system, for the common cold. However, those who also take Lipitor, Celebrex and Aleve face an increased risk of liver damage. Echinacea also can be harmful for those who have multiple sclerosis, diabetes, HIV infections or allergies.

Dr. Grossberg and his co-author Barry Fox make it clear that they're not anti-herb or anti-medicine.

"There just are a lot of things people can take that have a lot of bad interactions. And on some level it makes sense for them to think that what they're doing is safe. They associate natural remedies with nature and think if the supplement wasn't safe, they couldn't pick it up without a prescription.

"Hopefully this will get them to think more about it so they look before they leap. People can look up what they're thinking of taking and see if there's efficacy. And they should always talk to their doctor about everything they're taking."

Many doctors don't know much about herbal remedies, which have been used as medications for thousands of years.

"When I trained, there was nothing like this in our medical education," says Dr. Grossberg, who graduated from medical school in 1975. "The younger doctors are more likely to know this than older doctors."

Elderly people, he says, use herbal remedies and don't always tell their doctors and pharmacists. They should.

"A lot of our older patients are buying herbals and botanicals. In addition, while those over 65 represent about 14 percent of the population, they consumer 40 percent of over-the-counter medications," he says.

Written from a news release by Saint Louis University.