The agency says amounts as small as one teaspoon can cause serious health problems. They are telling companies not to sell the powder in bulk quantities.

Step away from the powder.

That’s the warning the Food and Drug Administration (FDA) has issued to consumers regarding caffeine powders that are now sold all over the internet.

On Friday, the federal agency issued an advisory on what it called the “dangers of highly concentrated or pure caffeine products.”

Agency officials said the powders had been linked to at least two deaths in otherwise healthy individuals.

“These products present a significant public health threat because of the high risk that they will be erroneously used at excessive, potentially dangerous doses,” the FDA advisory stated.

The advisory “clarified” that dietary supplements containing these powerful caffeine powders are illegal when sold in bulk quantities directly to consumers.

FDA officials said because of the “significant public health concern,” this ban was taking effect immediately.

The advisory added that the FDA is “prepared to take steps right away to begin removing illegal products from the market.”

There are more than a dozen caffeine powders sold on the internet, including on

Many of the products’ websites talk about “energy” and “alertness” in relation to the products.

None appear to have a warning on the dangers of consuming too much of the powder.

FDA officials say a single teaspoon of pure powder caffeine can contain 3,200 milligrams (mg) of caffeine. That’s equivalent to between 20 and 28 cups of coffee.

A half cup of liquid caffeine, agency officials add, can contain 2,000 mg of caffeine. By comparison, a can of caffeinated soda contains 35 mg of caffeine.

The officials note the “recommended safe serving” of pure caffeine products is 200 mg. That’s about 1/16 of a teaspoon of powder, or 2.5 teaspoons of a liquid.

“Regardless of whether the product contains a warning label, such products present a significant and unreasonable risk of illness or injury to the consumer,” the FDA advisory stated.

The officials add that this advisory does not cover dietary supplements that contain caffeine that are sold in premeasured packets or are sold as tablets or capsules.

It also doesn’t involve over-the-counter prescription drugs with caffeine or traditional beverages that are caffeinated.

One of the biggest problems FDA officials see is that these products are sold in bulk powder packages or liquid containers of one gallon or more.

Agency officials say consumers don’t have the proper tools to measure these products in safe, small amounts.

They also note that even with the right measuring tools, a consumer can use a “heaping scoop” instead of a level one, raising caffeine amounts to dangerous levels.

They add that these products can also appear to be “safe household items,” leading to unsafe consumption.

“The consequences of a consumer mistakenly confusing one of these products could be toxic or even lethal,” the FDA advisory stated.

All these health concerns prompted the FDA in 2015 and again in 2016 to issue warning letters to seven distributors of pure powdered caffeine.

However, since then the agency “has continued to see a proliferation of similar products being sold online. The FDA intends to carefully review any dietary supplement products that contain potentially dangerous amounts of caffeine in any form, and the agency will continue to take action when products put consumers at risk,” the FDA advisory stated.

On its website, the Mayo Clinic states that 400 mg of caffeine per day is safe for most healthy adults.

They note this is the equivalent of four cups of brewed coffee, 10 cans of cola, or two “energy shot” beverages.

They add that caffeine is not a healthy choice for children, and teenagers should limit their caffeine intake.

They also recommend against mixing caffeine with substances such as alcohol.

Kristin Kirkpatrick, MS, RD, LD, a licensed, registered dietitian and manager of Wellness Nutrition Services at the Cleveland Clinic Wellness Institute, agrees with the FDA advisory.

“Consumers should know how much caffeine they are consuming in really any product that contains caffeine,” she told Healthline.

Kirkpatrick notes that heavy levels of caffeine can be dangerous for anyone, but they can be particularly unsafe for people who metabolize caffeine more slowly or have heart abnormalities.

She adds that many people don’t realize how much caffeine they are taking in during a day. A person might have an expresso in the morning, an energy drink at lunch, and more caffeine at dinner.

“There is a dose dependent factor here and we always need to remember that caffeine is, in fact, a stimulant that greatly impacts the central nervous system,” Kirkpatrick said.

There are side effects for overdoing it on caffeine, even if you don’t ingest it at dangerous levels.

“When you have one to two cups of coffee, for example, you may feel more alert and even have more energy due to the impact on the [central nervous system],” she explained. “Above this amount… you may start seeing an increase in blood pressure, irritability, nervousness, dizziness, muscle convulsions, etc. The effects of caffeine are quick as well.”