A woman suffered such "debilitating" lesions on her tongue after receiving a Covid vaccine that she ended up losing nearly 22 pounds (10kg).
The 60-year-old from Australia received a Pfizer vaccine, but with each shot her symptoms worsened.
Her side effects, alongside the lesions on her tongue, included a dry mouth and inflammation - all so painful to the point that she was left unable to eat.
Doctors unfortunately struggled to find the culprit for nine months - during which she lost a shocking 17 pounds (8kg).
Horrifically, by the time she was finally diagnosed, her swollen tongue had began to split open leaving deep, agonising sores.
Medics eventually diagnosed the 60-year-old with Sjögren's syndrome - an autoimmune disease that sees the immune system damage completely healthy parts of the body.
The condition attacks glands that produce moisture in the eyes, mouth, and other parts of the body.
Luckily, her symptoms were finally cured with a six-week course of topical steroids.
Doctors then went on to record the rare side effects in a report published last month in the American Journal of Case Reports.
It went to outline that the unidentified patient, from Australia, received three vaccine doses in total – two of which formed the initial course, as well as a single booster.
The journal said the unnamed patient developed sores in her mouth just three days after receiving the first dose of the Pfizer-BioNTech vaccine.
Her symptoms then partially abated, but after receiving a second dose, her symptoms returned more severely.
The 60-year-old then underwent a cadre of blood tests to rule out other diagnoses such as HPV and other infections.
After being referred to an rheumatology clinic with suspected Sjögren syndrome, doctors prescribed the patient with a variety of creams, including a benzodiazepine that when ingested orally can treat burning mouth syndrome.
However, these did little to alleviate her symptoms, and when doctors prescribed an oral steroid, the treatment stopped because it was causing the woman abdominal pain, as the journal outlined: "Her symptoms progressed; therefore, her primary physician prescribed oral prednisolone 30mg per day for 2 weeks, which resulted in 60 per cent improvement in symptoms; however, this was ceased after 5 days due to significant abdominal discomfort."
The condition left doctors puzzled, especially given that they were not able to diagnose her condition.
And while oral symptoms can be associated with the Pfizer vaccine, they are uncommon and likely under recognised by providers who do not specialise in oral healthcare.
Similar symptoms were also documented in patients infected with coronavirus - which led to the condition being dubbed "Covid tongue".
However it has been noted that, oral sores are not a new phenomenon after a vaccine.
They have previously been spotted in people following flu, hepatitis B and papillomavirus jabs.
But, only a handful of cases have been reported after Covid vaccines - despite billions of doses being administered around the world.
And, writing in the American Journal of Case Reports, the doctors said: "A subsequent review of the timeline of history and medications, including vaccinations, identified a clear relationship between the exacerbation of oral symptoms after each [Pfizer-BioNTech] vaccination."
Following clinical immunology review, the 60-year-old was prescribed a topical oral preparation, with it initially being taken three times a day.
After two weeks, it was reduced to twice daily, and then once daily for two weeks before ceasing.
With the symptoms finally gone, the report wrote: "The tongue fissures and stomatitis gradually resolved completely, with associated improvement in xerostomia (Figure 2).
"She was able to resume a normal diet, and at the last follow-up, had not had recurrence of disease."
Meanwhile, the Centers for Disease Control and Prevention's (CDC) database for Covid vaccine side effects has noted that it does not include oral symptoms.
A major caveat is that reporting of the adverse effects is voluntary, and therefore cases may be underreported.
The doctors wrote: "Additionally, this case highlights that in some patients a clear unifying diagnosis may not always be possible.
"When the diagnosis is not clear, a symptom-based approach can still be applied based on the clinical features to provide the most benefit to the patient, particularly when symptoms significantly affect quality of life."
They added in the case study: "This case demonstrates that oral symptoms can be associated with BNT162b2 vaccination, which is likely under-recognised by practitioners outside the field of oral health."
The most common side effects of receiving a COVID vaccine include pain at the injection site, headaches, fatigue, dizziness, nausea, chills, and fever.
