The Food and Drug Administration is warning consumers about unauthorized kits that are being marketed to test for coronavirus in the home.

“At this time, the FDA has not authorized any test that is available to purchase for testing yourself at home for COVID-19,” the agency said today in a news release.

Several companies have begun marketing test kits that let consumers to take their own samples, using nasal swabs and/or saliva collection kits, and then send them in to a lab for analysis. In some cases, the consumer is asked to provide a spit sample, as an alternative or a backup.

In today’s alert, the FDA left the door open for the use of such tests.

“The FDA sees the public health value in expanding the availability of COVID-19 testing through safe and accurate tests that may include home collection, and we are actively working with test developers in this space,” the agency said.

The alert advises consumers to follow guidelines from the Centers for Disease Control and Prevention, and speak with your medical provider if you have symptoms of COVID-19, such as fever or a dry cough. “Your medical provider will advise you about whether you should get tested and the process for being tested with an appropriate test,” the FDA said.

The problem with that advice is that many consumers, and even some physicians, are still in the dark when it comes to the availability of coronavirus tests. Despite assurances that millions of tests are being distributed, there’s been a blizzard of complaints about the inability to get tested, even when such tests have been recommended by healthcare providers.

To make testing more available, the FDA has started giving labs and state public health officials more leeway for creating and validating tests for the SARS-CoV-2 virus. Several diagnostic companies, including Roche and ThermoFisher, received the agency’s expedited go-ahead under the terms of Emergency Use Authorization.

At least three companies — Everlywell, Carbon Health and Nurx — say they’ve cleared the regulatory hurdles and will allow consumers to collect samples that can be sent in for lab analysis. Lemonaid and Scanwell say they’re still putting the pieces in place for at-home tests that would be offered under the FDA’s emergency rules and analyze finger-prick blood specimens.

The existing sample collection systems typically involve partnerships with labs that have received the FDA’s go-ahead, as well as with clinics that provide follow-up consultations.

Even if the test provider is legit, there are caveats to keep in mind. First of all, taking a sample with a nasopharyngeal swab isn’t easy. President Donald Trump, who was tested last weekend, complained that the procedure is “a little bit difficult” and “not very nice to do.” Health experts are reportedly working on a self-swabbing system that would be easier for consumers.

Then there’s the cost: Even though the companies say they’re trying to keep the costs down, customers would still be charged a fee ranging from $70 to $165 or more. A newly signed law provides for free coronavirus testing, but it’s up to the customers to figure out how much of the cost will be covered by insurance. STAT News also notes that the process of receiving the kit, shipping the samples to the lab and getting the results back could take an uncomfortably long time.

The best course is to follow the FDA’s advice: Discuss your symptoms and what to do about them with your medical provider — and don’t try to go it alone, even if you’re cooped up at home.

Update for 12:50 p.m. PT March 21: We’ve updated this report to provide a better characterization of the test kit that Lemonaid and Scanwell plan to offer. If you are aware of fraudulent COVID-19 test kits, you can report them to the FDA via the unwieldy email address 2019-nCoV-FDA-IMG-Operations-Fraudulent-Products@fda.hhs.gov — or just click on this link.

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