A woman who fell asleep at the beach developed severe sun poisoning - leaving her face so swollen she looked like an "alien" and her own sister didn't recognise her."

Bela Chatwin, 21, was left unrecognisable after her face swelled up severely due to sun poisoning on holiday.

Sun poisoning is a severe case of sunburn - usually a burn from ultraviolet radiation that inflames the skin.

The interior design assistant accidentally fell asleep on the beach without suncream, prompting the reaction.

Doctors told her she had developed sun poisoning and it took her three weeks to recover, aided by steroid-based skin creams.

Her face became so swollen that her own little sister, Aero Chatwin, then three, couldn't recognise her - and other people said she looked like "an alien"."

Bela says it transpired she has photodermatitis - a lifelong allergy to the sun - but she wasn't diagnosed until the sun poisoning alerted doctors to it.

She had never known because she had always applied sun cream so diligently before this point.

Bela now swears she'll never make the same mistake again - and encourages others not to underestimate the importance of using SPF.

Bela, from Lehi, Utah, US, said: "That day it was just me and my friend at the beach, and it was bright but cloudy and not that hot."

"I fell asleep for about five hours - I thought my friend would wake me up, but she fell asleep too."

"The next day I was bright red, and my face started getting puffy and blistered."

"I realised it was a bigger deal than just normal sunburn - at its worst, I could barely open my eyes."

"Total strangers were coming up to me asking what was wrong and my sister didn't even recognise me."

"I went straight to the doctor, and he told me it was sun poisoning, and it was the worst case he had seen."

"Ever since then I've been so careful in the sun because I know I'm allergic and I never want to go through that again."

Bela said she had always been part of an "outdoorsy" family, but they had always ensured she wore suncream."

She never knew she had an allergy to the sun until she went on holiday to San Diego, California, US, in April 2018 with her friend and their family.

On one of the days the two pals, both 16, went on a solo trip to the beach on a cooler day.

Bela said the temperature was only between 18 and 22 degrees centigrade, and it was cloudy.

She intended to apply sun cream but fell asleep before she had the chance - and ended up asleep on the sand for five hours without sun protection.

When she woke up, her skin wasn't initially red, but she said she felt "exhausted" despite her unplanned nap."

But the following day, her skin was bright red, which she put down to sunburn - but then things took a turn for the worst.

She said: "The day after that, I started getting puffy and there were blisters on my chin and cheeks."

"I panicked - I started to realise it was a bigger deal than just sunburn, and it was so painful too."

"The day after that, my face was completely swollen - I could barely open my eyes."

"The blisters began to pop, and it was so gross - whenever I went outside, I'd wear a surgical mask to cover up."

"Random strangers kept asking about it - one even grabbed some aloe vera from their yard to give me."

"Most people's reaction was to be scared of me - they would look at me like I was an alien."

As soon as Bela returned home, she got an emergency doctor's appointment to find out what was wrong.

She said: "I got home, and my face was so puffed up that my little sister didn't even recognise me."

"I wanted to feel cute, but I felt so ugly."

At this point the reaction had gone beyond just her face - she was throwing up several times a day.

She said even the doctor was shocked at how extreme her reaction was - but was quick to see she had an undiagnosed allergy.

Bela was told she had sun poisoning, as a result of having photodermatitis, and was prescribed various medications.

She said: "It took about three weeks to get fully better - but at first I was worried I'd look like that permanently."

"I cried about it a lot, I didn't want anyone to see me - I got told I looked like a turtle or an alien."

Since then, Bela said she's been very careful to always apply sun cream, even if it's cloudy or not that hot.

And since then, she said she hasn't had a reaction - and has vowed to never let it happen again.

She added: "Now I know you should be careful no matter what - it could happen to anyone."

"Looking back, I can laugh about it now - how I looked was hilarious."

"But it was absolutely horrific to experience, and I never want that to happen again."