Fact Check-Shell Flucloxacillin Prescription Antibiotic Capsule contains iron oxide, a common dye used to protect the drug inside


Social media users shared videos showing black material in the gel capsule of the antibiotic flucloxacillin, which appears to be attracted to the magnets when dissolved in water.

The capsule shell may contain iron oxide, a coloring agent, which is magnetic. Its use is heavily regulated and there is no evidence to suggest that it is dangerous.

Flucloxacillin, which is only available in the UK by prescription (here), is used to treat a range of infections, including lung infections, such as pneumonia, as well as skin and wound infections.

Videos (here, here) shared online show a home science experiment. During the experiment, the envelope of the flucloxacillin capsule is broken and the drug is released.

The shell, half of which is black in color, is then dissolved in a glass of hot water.

When a magnet is slid along the outside of the glass, a black drop will appear to follow the path of the magnet. In some videos, people can be heard suggesting that the material is unsafe.

“Imagine you have a 5G electromagnetic pulse that you could manipulate this with… I wonder if that’s possible? Well I can certainly handle it with that, ”says a man leading the experiment in a video, as he moves the magnet through the glass (here).

An open access resource provides details on the inactive ingredients, also known as excipients, used to package any medicine authorized in the UK. It can be viewed at www.medicines.org.uk/emc#gref.

On the flucloxacillin page here, the capsule shell contains iron oxide (E172).

It is a legal requirement of the UK Human Medicines Regulations 2012 that the ingredients of a medicine are listed on the package leaflet provided with each package here.

Iron oxide, also known as ferric oxide, is used in food, cosmetics, and the pharmaceutical industry (here).

“Iron oxide is used in drugs as a coloring agent – it helps distinguish drugs so they don’t all look the same,” explained Hannah Batchelor, professor of pharmacy at the Strathclyde Institute of Pharmacy and Biomedical Sciences, University. from Strathclyde. to Reuters in an email.

“The iron oxide also makes the capsule shell opaque, which reduces the penetration of light and thus contributes to the stability of the drug.”

The color additives allowed in UK medicines are determined by UK law, still linked to EU food law since Britain left the bloc (here).

“Drug regulations in the UK are in line with that in Europe and the US where each drug must demonstrate a good safety profile, and the iron oxide level will have been reviewed to ensure that ‘it’s below the daily limit,’ Batchelor said. .

“There is no reason to believe this is dangerous. “

An Acceptable Daily Intake (ADI) of 0-0.5 mg / kg bw / day of iron oxide has been set by the Joint FAO / WHO Expert Committee on Food Additives (JECFA) (here).

This means that for a 50 kg adult, 25 mg could be ingested daily for a lifetime without appreciable health risk.

The UK government says additives can only be used if they have been tested and found to be safe for their intended use. He adds that the science on additives is strictly discussed here.


Missing context. The shell of some medicine capsules may contain iron oxide, which is magnetic, as a coloring agent. Iron oxide, which is also used in foods, is highly regulated and there is no evidence to suggest that it is dangerous.

This article was produced by the Reuters fact-checking team. Read more about our work to check social media posts here.


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