A tragic case highlights a critical concern for users of weight loss medications, as Dawn Clegg, 52, from Lancashire, was diagnosed with terminal soft-tissue sarcoma after mistaking early cancer symptoms for side effects of her prescribed type 2 diabetes drug, Mounjaro (tirzepatide). Initially experiencing chest pain in March, Ms. Clegg attributed her discomfort to common side effects like indigestion, nausea, constipation, and diarrhoea, which are well-known to accompany the 'King Kong' of weight loss drugs. Mounjaro functions by stimulating insulin production, reducing liver glucose, and slowing digestion. However, when her chest pain persisted, she sought emergency medical attention. Subsequent X-rays and scans revealed ominous shadows on her lungs, kidneys, and breast, leading to the devastating diagnosis of soft-tissue sarcoma, with doctors giving her less than a year to live.

Soft-tissue sarcoma is a rare, aggressive cancer that can originate in various soft tissues, including muscles, fat, blood vessels, ligaments, and tendons. While a lump is the most common sign, other symptoms like abdominal pain and constipation can mimic the side effects of powerful weight loss jabs. Although growths on her kidneys and breasts were found to be benign, the lung growth was cancerous. Her husband, Aaron, 51, expressed their devastation. With over 100 types of sarcoma affecting approximately 5,300 people annually, the difficulty in identifying the specific type of sarcoma in Ms. Clegg's case has made finding effective treatment challenging, severely dimming her prognosis.

Healthcare professionals are now urgently advising weight loss jab users to remain vigilant and not dismiss potential warning signs of serious underlying conditions. Dr. Jack Ogden, an NHS GP, emphasized the ease with which both patients and clinicians can misattribute symptoms to obvious causes, such as weight loss injections, when a more severe condition might be present. This concern is underscored by another patient's case, who, while on a GLP-1 weight loss drug like Ozempic, experienced persistent fatigue, nausea, and early satiety—symptoms that led to a diagnosis of stage two stomach cancer. Dr. Ogden advises monitoring persistent symptoms, keeping a log of side effects, and seeking prompt medical advice for anything unusual.

Superintendent pharmacist Ana Carolina Gonclaves echoed these warnings, noting that while indigestion, heartburn, and abdominal pain are common side effects of these jabs, they can also signal deadly liver, bladder, pancreatic, or stomach cancers. With the rising use of weight loss injections in the UK, the potential for confusion, especially where cancer symptoms overlap with drug side effects, is growing. She specifically pointed out that thyroid swelling or a lump in the neck, which might be dismissed as an injection side effect, could indicate thyroid cancer. Manufacturers of Mounjaro (Eli Lily and Company) and WeGovy (Novo Nordisk) have previously cautioned about the drug's potential to cause thyroid tumours, including cancer, urging users to watch for symptoms like a lump or swelling in the neck.

Gonclaves further explained that nausea, another frequent side effect, can also be a symptom of liver, bladder, or pancreatic cancer, stressing the significant overlap between symptoms of different organ cancers due to their proximity. Main symptoms of thyroid cancer include a hard lump in the throat, a hoarse voice, sore throat, difficulty swallowing, and pain in the front of the neck. Kevin Joshua, clinical lead at Juniper, warned of the danger that individuals might attribute persistent or worsening symptoms to medication rather than consulting their GP, a delay that can be critical for cancer treatment and survival. Doctors advise consulting a medical professional if symptoms are persistent, severe, or accompanied by red-flag signs like vomiting blood, blood in the stool, jaundice, or a lump.

These warnings coincide with new research suggesting that weight loss jabs may increase the risk of kidney cancer, a 'silent killer' that is now affecting more individuals under 50. The largest study of its kind, tracking nearly 44,000 overweight and obese individuals for up to 10 years, found that while the drugs were associated with a 17% lower overall cancer risk (with significant reductions in ovarian and womb tumours), there was a disturbing signal for kidney cancer. Patients on these jabs were approximately one-third more likely to develop kidney cancer than non-users, with the risk being highest among those under 65 and individuals classified as overweight. Doctors caution that by the time common symptoms such as blood in the urine, persistent back pain, or a lump under the ribs appear, it is often too late for successful treatment. In the UK, almost 14,000 people are diagnosed annually, leading to 4,700 deaths. Early detection can lead to a 75% survival rate over five years, but this plummets to just 18% once the cancer has spread.