WASHINGTON -- The Food And Drug Administration warned consumers Friday against buying products online that claim to diagnose, prevent, or treat H1N1/ swine flu.

The agency said many of those products can pose serious health threats. One drug they tested that was represented as Tamiflu contained only Acetaminophen. Others contained impure ingredients or unrecommended amounts of the correct ingredients.

Officials said they've seen a spike in online sales of supposed H1N1 vaccines, as criminals capitalize on consumers' fears.

There are only two antiviral drugs approved by the FDA for treatment of H1N1 flu: Tamiflu and Relenza. The agency is urging consumers only to buy FDA-approved products from licensed pharmacies located in the U.S.

For more information, see the FDA's website.