CNN  — 

The US Food and Drug Administration sent a warning to 15 companies that have illegally sold cannabidiol products, better known as CBD, by adding it to food or marketing it as a dietary supplement.

The agency also released a consumer update about CBD, the non-psychoactive ingredient in marijuana increasingly used to treat pain and anxiety. Until it learns more about the effectiveness and safety of CBD, the FDA said it cannot generally recognize the ingredient as safe or approve products that contain it.

“We remain concerned that some people wrongly think that the myriad of CBD products on the market, many of which are illegal, have been evaluated by the FDA and determined to be safe, or that trying CBD ‘can’t hurt,’” FDA Principal Deputy Commissioner Amy Abernethy said.

The FDA sent letters to the following 15 companies for selling CBD products that violate the Food, Drug and Cosmetic Act, for marketing the products to treat illnesses or for therapeutic use, claiming it’s a dietary supplement or adding it to food for humans and animals.

-Red Pill Medical Inc. of Phoenix, Arizona

-Pink Collections Inc. of Beverly Hills, California

-Healthy Hemp Strategies LLC (does business as Curapure) of Concord, California

-Koi CBD LLC of Norwalk, California

-Sabai Ventures Ltd. of Los Angeles, California

-Organix Industries Inc. (does business as Plant Organix) of San Bernardino, California

-Whole Leaf Organics LLC of Sherman Oaks, California

-Infinite Product Company LLLP (does business as Infinite CBD) of Lakewood, Colorado

-Sunflora Inc. of Tampa Florida/Your CBD Store of Bradenton, Florida

-Daddy Burt LLC (does business as Daddy Burt Hemp Co.) of Lexington, Kentucky

-Bella Rose Labs of Brooklyn, New York

-Private I Salon LLC of Charlotte, North Carolina

-Natural Native LLC of Norman, Oklahoma

-Apex Hemp Oil LLC of Redmond, Oregon

-Noli Oil of Southlake, Texas

It’s not illegal to sell products that aren’t approved by the FDA, but it is illegal to add certain drug ingredients to products unless they’re approved food additives (CBD is not). CBD is also not characterized as a dietary supplement under the Food, Drug and Cosmetic Act, the agency said.

Some of the companies marketed products to infants and children, the FDA said, who may be at a heightened risk for negative side effects of CBD due to differences in the way they metabolize, absorb and excrete the ingredient.

Reports of pesticides and heavy metals in CBD have also raised questions about its safety and toxicity, Abernethy said.

The FDA has never evaluated the effectiveness of CBD products, the amount in a “proper” dosage, potential side effects of consuming the products and the manufacturing process.

The agency has only approved one prescription drug that contains CBD, Epidiolex, used to treat two forms of childhood epilepsy. Most other marketed CBD products contain different amounts of the ingredient, which the FDA hasn’t evaluated, the agency said.

Correction: This story originally used a photo that showed products made by a company not included in the FDA's list of companies. It's been updated.