'At 27, I developed acne overnight. Now I've just worked out why.'

I had completely forgotten what it was like to be self conscious about your skin. A luxury, I know.

When I was a teenager, I had pimples, sometimes lots of them, sometimes painful, and often impossible to hide. I remember seeing an older relative at a family gathering and her exclaiming, ‘What’s going on with your skin?!’ as though I had any idea, and public acknowledgement of it would somehow make it go away.

The hardest part about having regular breakouts, especially as a teenager, is that there’s no discernible cause. People might insist that your skin would clear up if you would just drink more water, eat more vegetables, cut out dairy, or wash your face with a very specific and usually very expensive product, but the fact is, it’s hormones. And genes. And a bunch of other factors that are entirely out of your control.

But when I woke up at 27 with a painful breakout all over my forehead, chin, chest and back, after having only dealt with the odd pimple for years, it felt different. Surely this doesn’t just happen out of the blue. The entire texture of my skin had changed. It was oily and sore and these pimples weren’t like the ones I was used to. They were painful lumps, in some weird places (on the back of my ear… really?), and after a few days, I realised they weren’t going away. Every day there were more.

I racked my brain for anything in the last few weeks that could’ve triggered it. A face mask? A facial? A new body wash?

I’d used a face mask a few weeks prior, but that didn’t explain my chest and back. It also felt like something had fundamentally changed about my skin – this wasn’t just a bit of a breakout.

Then it hit me.

I had gone to the doctor for a blood test, and when I got the results, it turned out I had a vitamin b12 deficiency. So the doctor had recommended a set of three b12 injections.

It was about a week after the first injection that I woke up with acne.

When I looked it up, I found a number of research studies investigating this phenomenon.

The link between vitamin b12 injections and acne was first observed in the 1950s, and the ‘eruption’ usually occurs abruptly after the first or second injection. Females tend to be more frequently affected, and (thankfully) the acne usually fades shortly after the injections have stopped.

A seminal study led by researchers from the University of California and published in 2015 tested 10 participants who were all given vitamin b12 supplements. Of those 10, only one broke out in pimples.

“Our findings suggest a new bacterial pathogenesis pathway in acne and provide one molecular explanation for the long-standing clinical observation that vitamin B12 supplementation leads to acne development in a subset of individuals,” the study said.

"Our study... provided evidence that... interactions between the host and the skin microbiota play essential roles in disease development."

The mechanism by which an excess of b12 is thought to contribute to acne is complex and not clearly delineated yet, but many researchers are dedicated to further understanding it.

On the one hand, it would be dangerous for the public to avoid vitamin b12 supplements out of fear that they'll cause them to break out. First, only a relatively small percentage of people have this reaction, and second, the benefits of vitamin b12, which include playing a major role in how your body creates energy, as well as protecting your heart, brain and bones, far outweigh the side effect of acne.

But it's important for people to be informed when it comes to their bodies, and at no point did my doctor warn me that acne was a potential side effect of the b12 injections.

Ideally, those of us who can (some people need injections to treat long-term health conditions) should be eating enough foods rich in vitamin b12 so we won't need injections to treat the deficiency. But for now, I'll be finishing the set of injections. And waiting impatiently for the acne to subside.