An iron stain.

Simultaneously better and worse than it sounds.

You may have noticed tough Western Bulldogs winger Rylie Wilcox donning a single protective sleeve in matches this year.

It's to protect her upper arm from the sun, as well as the rough and tumble of football, after she suffered a rare side effect from an iron transfusion.

It can occur during "extravasation", when iron leaks from the veins into the surrounding tissue during an infusion, leaving a large patch of discoloured skin, which can be permanent.

"Back in 2023, I went and got an iron infusion, and basically I had an adverse reaction to the iron infusion, and got an iron stain. This reaction isn't impossible, but it's also not the most common side effect," Wilcox told AFL.com.au.

"I now undergo laser treatment to basically get rid of the stain. As a result of the laser treatment, my skin on my arm gets really sensitive to sunlight, and basically this sleeve is just to keep it protected from the sunlight and weather."

Sessions last just a handful of somewhat painful minutes, but protecting the vulnerable skin is an ongoing process. 

Maintaining a comfortable body temperature while playing is a balancing act for the lightly framed Wilcox – the choice of one sleeve in sunny conditions is so she doesn't overheat in a long-sleeve, while she wears it during night games for additional warmth.

The sleeve itself isn't anything special, just purchased from her local Chemist Warehouse, but did have to be ticked off by the AFL as an additional garment. 

Casey Sherriff has a shorter version over her previously broken arm and surgical scars, while Port Adelaide men's player Mani Liddy wears a single leg sleeve to protect thin skin and scars over his knee.

"Basically, just think of the treatment like removing a tattoo, and I do it every three months," Wilcox said.

Wilcox has since switched from transfusions to iron tablets, needing to supplement her diet due to her Coeliac disease, which limits her ability to absorb iron as well as gluten.

"I was diagnosed in 2017 when I was in year seven, because I wasn't actually growing. Mum decided to get all these tests done, and it came back that I was Coeliac," she said.

"Once we knew, I was able to [tailor my diet accordingly], and I shot up about 20cm (she now stands at 158cm). I always joke that gluten stopped me from being taller. It's definitely genetics, but we're blaming the gluten."

Having been on a gluten-free diet since she was 13, Wilcox is now well adept at fuelling herself properly for sport, whether that was for hockey as a teenager, or elite football.

"You can still get your carbs from different food. I have a lot of rice, potatoes, that kind of stuff," she said.

"It's not much different. I think it's just substituting your bread and pasta, with gluten-free pasta, or gluten-free bread. Sometimes I need something a little extra, because it doesn't have the same nutrients as normal bread or pasta. Our dietitian (Jess Fell) has helped me a lot with that, ensuring I have the right nutrients and energy for games and training.

"I have my own little gluten-free lolly stash at the Doggies, so I always snack on them during matches. I even bring my own stuff to games, and the dietitian will always have something for me, too. They look after all the girls who have dietary requirements."