A collection of homeopathic treatments in the office of homeopathic practitioner Begabati Lennihan, in Cambridge, Mass., includes preparations made with robinia, castor bean, silver phosphate and clippings of wintergreen and rosemary, shown in this Feb. 6 photo. Homeopathic remedies, such as Zicam, are not tested by federal regulators.

Cambridge, Mass. ? The unsettling little secret of Zicam Cold Remedy finally spilled out this week. Though widely sold for years as a drug for colds, it was never tested by federal regulators for safety like other drugs. And that was perfectly legal — until scores of consumers lost their sense of smell.

One little word on Zicam’s label explains all this: “homeopathic.”

Zicam and hundreds of other homeopathic remedies — highly diluted drugs made from natural ingredients — are legally sold as treatments with explicit claims of medical benefit. Yet they don’t require federal checks for safety, effectiveness or even the right ingredients.

They’re somewhat similar to dietary supplements, which use many of the same natural ingredients and also aren’t federally tested for safety or benefit.

Many scientists view homeopathic remedies as modern snake oil — ineffective but mostly harmless because the drugs in them are present in such tiny amounts.

But an Associated Press analysis of the Food and Drug Administration’s side effect reports found that more than 800 homeopathic ingredients were potentially implicated in health problems last year. Complaints ranged from vomiting to attempted suicide.

In the case of Zicam, the FDA says it tied the drug to reports from 130 consumers who said they lost their sense of smell.

The agency on Tuesday told Zicam maker Matrixx Initiatives to stop marketing three products that carry zinc gluconate: Zicam Cold Remedy Nasal Gel, Nasal Swabs and discontinued Swabs in Kids’ Size. The agency said the drug must be tested for safety and benefit, like a conventional drug, before it is again marketed. And the FDA warned people not to use the three Zicam products.

“It never occurred to me they could be dangerous and there was no kind of oversight — like the FDA — that ensured there was safety,” says former Zicam user David Richardson of Greensboro, N.C. He has complained to the FDA about losing his sense of smell and filed his case with a lawyer for a future lawsuit, joining hundreds of others who have claimed in recent years that they lost their sense of smell from Zicam cold products.

In its review of homeopathy, the AP also found that:

• Active homeopathic ingredients are typically diluted down to 1 part per million or less, but some are present in much higher concentrations. The active ingredient in Zicam is 2 parts per 100.

• The FDA has set strict limits for alcohol in medicine, especially for small children, but they don’t apply to homeopathic remedies. The American Academy of Pediatrics has said no medicine should carry more than 5 percent alcohol. The FDA has acknowledged that some homeopathic syrups far surpass 10 percent alcohol.

• The National Institutes of Health’s alternative medicine center spent $3.8 million on homeopathic research from 2002 to 2007 but is now abandoning studies on homeopathic drugs. “The evidence is not there at this point,” says the center’s director, Dr. Josephine Briggs.

• At least 20 ingredients used in conventional prescription drugs, like digitalis for heart trouble and morphine for pain, are also used in homeopathic remedies. Other homeopathic medicines are derived from cancerous or other diseased tissues. Many are formulated from powerful poisons like strychnine, arsenic or snake venom.

Homeopathy sprang from the inventive — some would say fanciful — mind of German physician and chemist Samuel Hahnemann in the late 1700s. Experimenting on himself, he became convinced that if an ingredient causes a symptom in a healthy person, it will treat the disease that causes the same symptom. He also theorized that diluting ingredients to minuscule, even untraceable, concentrations paradoxically makes them more powerful.