Homeopathic products (the term remedies implies they might re-mediate something) have been recalled because of impurities. However, in Onion-worthy irony, it has turned out that the impurities might be antibiotics – that is actual medicine, albeit inappropriate for the conditions for which they are advertised.

Homeopathic company Terra-Medica voluntarily recalled batches of certain products in liquid, tablet, capsule, ointment and suppository form as a result of US Food and Drug Administration findings that these may have contained penicillin or its derivatives.

Normally the only harm from homeopathy is to the wallet, or through failing to take medicines that actually pass testing. However, in this case the media release notes, “In patients who are allergic to beta-lactam antibiotics, even at low levels, exposure to penicillin can result in a range of allergic reactions from mild rashes to severe and life-threatening anaphylactic reactions.”

The FDA does not assess whether homeopathic products achieve their stated goals the way they do for actual medicines, but they do check for impurities or failures to include the claimed ingredients. Homeopathic manufacturers have been issued with FDA warnings before. As this letter makes clear, ensuring the “active ingredient” is actually included is not always a priority when the ingredient isn't actually that active.

Michael Marshall, vice president of Merseyside Skeptics told Wired UK , It's "[funny] to see homeopathic products recalled because, for a change, they actually contain some real ingredients." He warned however, there's "real cause for concern here."

On Neurological Steven Novella notes that the lower level of scrutiny of homeopathic medicines means it is possible for companies to produce a product with an active ingredient and then market it as homeopathic so it does not need to go through the safety testing that would be required if it was promoted for what is actually in it.

In the unlikely event that anyone reading IFLS takes homeopathy seriously enough to have these products in the house note that all the recalled items say “Distributed by SANUM USA” and have expiry dates between March 2014 and May 2018. A full list is available via the link above.

While most people seem unconcerned about the reverse situation, Associate Professor Neil Levy of the University of Melbourne mocked, “I am sure that lots of prescription medicines actually contain undetectable amounts of homeopathic ingredients. Undetectable! Can you imagine how potent that makes them? Every time you swallow an aspirin you risk an overdose.”

For those wondering why scientists are so contemptuous of homeopathy, it's not just that they have consistently been found to work no better than placebos it is also that the theory on which they are based contradicts everything we know about chemistry and a good part of physics and biology as well.

The original principle of homeopathy, that “like cures like” so that diseases could be treated by substances that produce similar symptoms is dubious, but not inherently ridiculous. However, the founder Samuel Hahnemann advocated diluting these substances to the point where many of the “remedies” offered contain not a single atom of the original product. Supposedly they leave their “essence” behind, which somehow gets more potent the less there is of it. The odd thing is that when water evaporates from the ocean we don't seem to get the trace energy of the salts, pollutants and even fish it was in contact with beforehand. According to homeopathy advocates this is because the energy is only maintained when the water is tapped against a leather saddle stuffed with horsehair, and that its strength increases the more the original mixture is diluted.

For the logical conclusion of how doctor's would operate if homeopathy actually worked, try this piece from Mitchell and Webb.