Nearly 160 people have reportedly been sickened this summer by eating mushroom-laced candy and chocolate bars that are widely available at vape and smoke shops, underscoring the dangers of a sprawling market of psychoactive products that pop up on store shelves with no review or regulation across the United States.

Two deaths now under investigation may be related to the candy, samples of which were found to contain an illegal form of psilocin, an ingredient in so-called magic mushrooms, according to federal health officials.

More than a third of those who became ill required hospitalization, suffering symptoms ranging from vomiting to loss of consciousness, seizures and hallucinations.

The illnesses were traced to Diamond Shruumz chocolates and gummies, which the company recalled on June 28, officials said. Since then, the Food and Drug Administration has said that it was aware that the candy continued to be sold, and the agency released a list of about 2,300 shops that it said carried the products.

Those items and other snacks, supplements and teas promising a mind-altering experience often contain ingredients like synthetic Delta-8-THC, or kratom, a botanical, that the F.D.A. considers hazardous.

They are commonly sold in stores and do not have to meet quality standards, nor do they carry restrictions on sales to minors.