With the coronavirus pandemic still in effect, consumers have turned to online retailers for supplies they cant find in stores. But buying items online, especially those that claim to prevent or treat COVID-19 , can be a risky move.

Amazon , the largest e-commerce retailer, has been criticized in the past for allowing vendors to sell defective or counterfeit products on its platform. At the start of the current health crisis, that problem became even more apparent. In late February, the company barred more than a million items from sale on its third-party marketplace due to price gouging and false claims related to COVID-19.

But that doesnt mean the website is now completely free of fraudulent or misleading product listings. Heres what you need to know before buying from Amazon, especially products that supposedly protect against the coronavirus.

Anti-COVID Products To Avoid On Amazon

Before the crackdown, it was really bad, said Robert Gross, co-founder and COO of Fakespot , a browser plugin that identifies fake product reviews and low-quality sellers. He said there were people selling fake N95 masks, expired masks, herbal remedies and vitamins that claimed to cure COVID-19, and other overpriced, fake or misleading products.

These products werent being offered by Amazon directly, but rather by its third-party sellers. As of 2018, 58% of physical products sold through Amazon were from third parties, and Amazon benefits because it doesnt pay for this inventory upfront. Its a really effective way to have enough inventory all around the world ... an unlimited supply of inventory from these third-party sellers, Gross added.

The drawback is that it provides an opportunity for scammers to take advantage of the platform. With the proliferation of these types of listings in the wake of the pandemic, Amazon had to temporarily shut down its third-party marketplace and restrict the types of products that are allowed to be sold.

Now the problem has resurfaced because they let third-party sellers back on the platform, and they have taken off [some of] the restrictions from COVID products, Gross said.

Misleading listings arent as widespread or egregious as before items like fake cures and testing kits have essentially been eliminated but youll still come across shoddy face masks, sanitizers that dont meet the CDCs guidelines for effectiveness and other products with questionable claims. (HuffPost reached out to Amazon for comment regarding what measures its currently taking to prevent these types of potentially fraudulent or misleading listings, but the company did not respond.)

You might find one or two people trying to get around the system, but Amazon has been very vigilant about shutting those [types of] listings down, Gross noted. Unfortunately, problems still exist because these are just general problems with Amazon overall.

When shopping on Amazon, its important to remain skeptical, especially when it comes to the following types of coronavirus-related products:

1. Counterfeit and used medical supplies

One of the most common categories for misleading or fake products is medical supplies, including masks and face shields. Some medical masks, for example, are listed for sale by poorly rated sellers that have been flagged by Fakespot for fake reviews. The problem with these types of listings is that the products can be overpriced, claim to be more effective than they really are or may actually be used, according to Gross.

2. Ineffective or counterfeit sanitizing products

When it comes to products like hand sanitizer and wipes , its crucial that they meet the Centers for Disease Control and Preventions guidelines for effectiveness. Unfortunately, a lot of the products sold online dont.

A study by online brand protection software provider Incopro found 272% growth in listings of fake hygiene-related products on e-commerce marketplaces such as Amazon, eBay and Wish in the first quarter of 2020, compared to the equivalent period in 2019.

Purchasing these products increases health risks due to consumers believing they are protecting themselves when the products have not been properly tested and are likely to be ineffective, the press release stated.

3. Ineffective UV sanitizer lights

Amazon has many listings for UV light sanitizer devices. However, many of these devices are cheap fakes that lack the power or spectrum-specificity to work at all, said Alex Magnin, founder of The Unwinder, which recently published a guide to evaluating UV light sanitizers . People are buying and using these products based on the trustworthiness of Amazon, but are not, in fact, killing bacteria and viruses on their phones, pocket goods and household items.

Magnin noted that there are multiple listings with images that depict cheap and/or underpowered LEDs. We found one listing (which has since been removed) that claimed to make the encironment [sic] safe within 10 seconds despite no disclosure of wattage and poor positioning of the LEDs.

Also, beware any UV sanitizing product thats designed for use on your skin. We know that powerful UV light can be used to disinfect surfaces that have been exposed to COVID-19. However, you should not buy any product that blasts your skin with UV light, as this can cause skin cancer, said Michael Bonebright, consumer analyst with DealNews .

4. Vitamins, supplements and oils

You should avoid any health product with claims that it can prevent or treat coronavirus. Not a single vitamin, supplement or medication has been proven to prevent or cure COVID-19, Bonebright said.

When it comes to products that fall under the purview of the Federal Drug Administration, there is an extensive guide to what the agency does and does not approve.

In particular, if a supplement or food claims to affect the structure or function of the human body without evidence, be aware that the FDA doesnt approve these statements, Bonebright said.

For example, if a vitamin C supplements label says it protects against scurvy, the statement is OK because studies have proven this to be true, he explained. However, if a Vitamin C label says it protects against coronavirus, the claim is false and against FDA rules.

5. Informational books

If you search for coronavirus treatments on Amazon, youll likely find several books in the results. However, these generally arent worthwhile publications.

People are selling books about the COVID cure or the COVID story, Gross said. What they are is basically articles people have taken off the internet and put in a PDF.

In other words, these types of publications arent written by experts and dont necessarily contain vetted information.

How To Spot A Shady Amazon Listing

Though Amazon has some measures in place to catch scammers and misleading product listings, theyre not foolproof. That means its up to you to use your best judgment when shopping on Amazon (or any other online retailer). Heres what to look out for.

Avoid anything that claims it can cure the coronavirus. Stay away from any product that claims to cure or prevent COVID-19. Thats the most obvious sign of a scam as nothing has been proven to prevent or cure the coronavirus, Bonebright said. And because fake coronavirus cures arent tested or vetted by any authoritative organization, theres a chance they could actually harm you.

Examine the photos. Another big giveaway of a fake product is the imagery, according to Gross. For example, the seller may use images that appear across multiple listings from various sites or that dont match the actual product. If the images are off, if something doesnt seem right ... run, he said.

Double-check the listings URL. Gross said that a common practice among fraudulent sellers is to buy existing listings for unrelated products that have a lot of positive reviews and simply swap out the product title and images. They instantly have thousands of glowing reviews, but for something other than what theyre actually selling.

By the time you realize you bought a faulty product, theyre gone. One way to easily check if this is happening is to examine the listings URL. If youre shopping for face masks, for example, but keywords in the URL are a book title or something else completely unrelated, its likely a fake or ineffective product.

Find out how long shipping takes. Because the coronavirus originated in China, there has been backlash (likely unwarranted) over products shipped from China. To avoid having their listings ignored in favor of products from the U.S., Gross said some third-party sellers in Asia will say items are based in the USA or shipped from the USA when theyre actually not.

That could be a sign that the seller is willing to stretch the truth on other details, too. If the shipping is not Prime, and its going to take a month to get your product, see where its coming from, Gross said.

Check seller ratings. Another easy way to avoid getting duped is to review feedback that customers leave for the seller, not just for the product. Actually take the extra 10 seconds to look at the seller, Gross said. If the seller has poor feedback, you shouldnt buy from them. There are so many great sellers on Amazon that actually deliver what they promise.

Be wary of new sellers. Theres not necessarily anything wrong with new sellers, but sometimes a new seller is a sign that someone got kicked off the platform and theyre coming back to do another scam, Gross said.

We found a listing for a basic plastic face shield (listed at a whopping $189.99) that was posted by a new seller that primarily sells baby clothes a reason to be cautious.

Look out for price-gouging. In addition to Fakespot, there are other free tools you can use to uncover potentially fake or misleading Amazon listings, including ones that gouge prices to take advantage of panic surrounding the virus.

One is Keepa , which tracks the price history on Amazon listings. If a products price suddenly spikes, its a sign that the seller is going against Amazons rules and engaging in predatory pricing a sign they arent trustworthy.

Plugins such as Honey or Wikibuy can also alert you to other websites that sell the product for a cheaper price, though its important to employ the same safety checks above to ensure its not just another scam.