A teenager almost died from multiple blood clots in her brain which doctors said were probably caused by a contraceptive pill she was taking.
Lexie Nash, 16, was sent home from school with a severe headache and neck pain in December 2017, just four weeks after being prescribed a new brand of contraceptive pill
Just 24 hours later, she was violently vomiting and had double vision.
Doctors first thought she had meningitis , but a CT scan discovered the cause was actually Cerebral Venous Sinus Thrombosis - where blood clots form in the sinuses which drain blood from the brain.
Her parents, Caroline, 38 and Paul, 47, were told to prepare themselves for the worst as medics battled to stabilise the teenager's blood pressure and heart rate, but after four weeks in hospital she recovered and was allowed home.
Despite her improvement, she is still suffering with fatigue, dizziness, headaches and slurred speech.
Lexie, from Churchdown, Gloucestershire, had been taking the contraceptive pill for nine months to control her heavy periods but had recently been prescribed a new brand called Marvelon, and says her doctors linked this pill to the clots.
The GCSE student said: "I was advised to take the pill to control my periods, but I never in a million years thought I could end up in hospital.
"I am an active person and never had any health complications before and was not made aware of any risks of the pill when it was prescribed until I fell ill with a critical condition.
"When it all started, it felt like my head was going to explode so my mum picked me up from school and as the pain continued, she took me to out of hours.
"I had never had a migraine before, so I assumed, they were right when they sent us home, but the pain was getting worse.
"I was projectile vomiting and could see two of everything, it was terrifying.
"My mum and dad rushed me to the hospital again and I held it together until I noticed my dad crying and then I knew it must be bad.
"I had blood clots on my brain and down my neck and multiple haemorrhages behind my eye which had caused the double vision.
"I am so shocked this has happened to me from taking the pill, I wasn't warned by the doctors who prescribed it to me."
Lexie was unable to communicate for four days after being diagnosed with the blood clots and doctors informed her parents to be prepared to say goodbye.
She spent four weeks at Bristol Children's Hospital while medics reduced the clots using a blood thinner infusion, and needed four months off school.
As her intracranial pressure - a build-up of pressure around the brain- was five times higher than the average person's, she also needed two lumbar punctures.
But tests in January 2019 showed the intracranial pressure in her skull was still too high, meaning she must take medication to prevent migraines.
Lexie said: "After being discharged, I still suffered severe headaches and was admitted again to Gloucester Hospital where a lumbar puncture was my only option, but it failed twice.
"On the third time it was successful - but after a couple of weeks I was admitted to Gloucester Hospital for reflex issues, muscle weakness, vision problems and terrible head pains.
"Doctors found out the pressure in my skull had again risen and over the next three months I had four more lumbar punctures as the pressure around my brain kept rising.
"After that it was decided it was getting risky performing lumbar punctures to often and I was put on medication to reduce the pressure, which gradually started working and improved my sight too.
"This gave me chance to focus on strength.
"Now, a year later I am still not 100 per cent, I suffer with fatigue and dizziness, short-term memory loss and I have problems with my speech, terrible head pains and body twitches."
Mum-of-two Caroline, a teaching assistant, said: "I had a feeling it was more than a migraine as she was in so much pain.
"Her heart rate was dangerously low and blood pressure high, the CT scans showed that Lexie had a rare condition that we had never even heard of.
"I was heartbroken, I was so scared we might lose her.
"I was worried sick, I didn't think she would ever be the same again, she was unable to talk and could only communicate with thumbs up or down.
"When we were told to 'be prepared' at the prospect of losing her I was scared and couldn't hold it together, it was a horrific experience.
"I want all mums to always trust their mother's instinct and if something doesn't seem right, go straight to the hospital.
"I was furious when the doctor told me Lexie's clots were due to the pill, I had no idea it could be this dangerous."
A spokesman for Marvelon manufacturer MSD (Merck, Sharp & Dohme) Limited said: "Marvelon is a combined oral contraceptive pill. It is licenced to be used as a contraceptive only.
"Its safety and efficacy was established in clinical trials in women aged 18 years and over.
"As with all medications, there can be side effects for some, and these are outlined in the accompanying patient information leaflet, which can be found in the Marvelon pill package.
"In the package leaflet for Marvelon, there is information on important things to know about hormonal contraception, including; what it is used for, what the user should know before she starts using Marvelon, when should she not use Marvelon, any warning and precautions regarding use, and potential side effects.
"This includes information outlines less common side effects such as blood clots which is listed as 'rare', based on reports from both clinical trials and observational studies, i.e. real world data. The package leaflet also encourages users to report any side effects.
"The safety and efficacy of our products is paramount to MSD.
"Therefore, MSD strongly recommends that if any patient is suffering an adverse reaction to any product or treatment, the patient or parent/guardian should speak with their healthcare professional or pharmacist to discuss their medicine use.
"The healthcare professional or pharmacist should then report any adverse events to the UK regulator, the Medicines and Healthcare products Regulatory Agency. The MHRA regularly review the safety and efficacy of products based on this reporting."