Image copyright @vitaminseafilm Image caption Beth Francis and Andrew Clark have filmed their swims for a documentary about trying to cure Beth's migraines

A migraine sufferer who started taking a regular dip in the cold sea to see if it would help ease symptoms has completed her 100 day challenge.

Beth Francis from Anglesey has seen her migraines reduce from 25 to 15 a month since her personal crusade started.

She is not sure if exercise, being outdoors or swimming has helped.

But she has vowed to continue and dozens of people joined her and her partner Andrew Clark for the 100th swim off Llanddona Beach on Sunday.

Image caption Beth and Andrew said they will continue to swim after completing the challenge

Speaking after the swim, Beth described the response to her efforts as "incredible".

"We've just been sharing what we've been doing through social media," she added.

"When we started it was just a journey, and it very quickly became much more than that.

"So we wanted to make this end day a celebration of everybody else involved as well."

Marine biologist Beth, 27, believes swimming in the sea has helped her condition, and she also found getting in the water soon after her symptoms started helped to reduce their severity of her migraines, although she continues to take medication and to see a specialist.

In 2017, the chronic migraines became so severe that Beth, who has been a sufferer since the age of nine, had to take sick leave from her first year of a PhD in marine biology at Bangor University.

Media playback is unsupported on your device Media caption How it all began...Beth and Andrew started filming their swims last year

She said she became "desperate" with symptoms including tinnitus, nausea, stomach aches and feeling numb on one side.

Migraine is very common - it affects one in seven British people - and can be hard to stop.

So Beth started regularly taking the plunge in the sea off Anglesey after reading research that "the sea can be used as motivation to exercise outdoors to influence health and wellbeing".

And she and filmmaker Andrew, 29, started publishing their experiences on social media, under the name 100 Days of Vitamin Sea.

Andrew said the decision to start swimming to try and improve their wellbeing was "easy".

"There's a lot of anecdotal stories floating round about the benefit to health of wild swimming and cold water swimming, or people who just get a kick out of it," he said.

"Living where we are, when we heard it could ease Beth's migraines or just make us a bit happier, it was an easy opportunity to take."

Image copyright @vitaminseafilm Image caption Beth allowed Andrew to film her good and bad days to highlight her condition

Their quest for a cure for Beth also saw the pair sharing their experiences on the BBC Breakfast TV sofa.

The project earned them an international accolade for patient-led action as well as support from other sufferers, with swimmers from around the world coming to Llanddola beach for her 100th swim.

"It seems to have touched a lot of people," said Beth.

"It has been an amazing journey."

She said a university research project was being set up, looking for participants to take cold showers rather than a dip in the sea, to see if it helped with their migraines.

A spokeswoman for The Migraine Trust said she was pleased Beth had found a way to deal with her own symptoms.

"If it is working for her, then that is very positive," she said.

"Migraine is an utterly miserable condition."