Some complementary health products (CHPs), such as health supplements, contain undeclared substances that pose significant health risks, according to a study.
Analyses of 727 CHP-related adverse event (AE) reports submitted to Singapore Health Sciences Authority (HSA) between 2017 and 2023 showed that most of these reports (68.1 percent) were attributed to health supplements. Chinese Proprietary Medicine accounted for 10.7 percent, while Malay traditional medicine, Jamu, Ayurvedic medicine, and homeopathic medicine collectively made up the remaining 22.8 percent. [Front Med (Lausanne) 2026:13:1872698]
Of the reports, 41 percent were classified as serious, including three fatalities. Serious AEs included Cushing’s syndrome (32 reports), liver injury (15 reports), anaphylaxis (10 reports), acute renal failure (6 reports), hypoglycaemia (3 reports), Stevens-Johnson syndrome (2 reports), DRESS syndrome (1 report), brain haemorrhage (1 report), exfoliative dermatitis (1 report), hepatic failure (1 report), and toxic epidermal necrolysis (1 report).
One of the main causes contributing to the AEs was contamination or adulteration with undeclared substances in CHPs (7.7 percent). Results of laboratory testing conducted on 73 products revealed that 56 (76.7 percent) contained undeclared drugs. Dexamethasone was the most frequently detected, followed by chlorpheniramine and prednisolone.
Sixty percent of the adulterated products were marketed for treating rheumatic joint pain, knee pain, back pain, gout pain, or inflammation. These products mostly contained NSAIDs such as piroxicam, ibuprofen, and diclofenac, as well as steroids including dexamethasone and prednisolone.
“Such adulteration presents considerable health risks, as prolonged usage of NSAIDs may lead to cardiovascular complications, including myocardial infarction and stroke. Furthermore, long-term unsupervised use of oral steroids can elevate blood sugar levels, potentially causing diabetes, hypertension, increased infection risk, and Cushing’s Syndrome,” the investigators noted.
Documented health risks
A notable example involved a product that contained dexamethasone, chlorpheniramine, ibuprofen, lovastatin, chloramphenicol, and tetracycline. A Chinese woman in her 60s who consumed this product for more than 9 months for joint pain reported symptom worsening when she attempted to reduce or discontinue its use. [https://www.hsa.gov.sg/announcements/press-release/hsaalert-xpe-fs]
Another significant case involved a product that contained dexamethasone, piroxicam, griseofulvin, and paracetamol. A Malay woman in her 60s who used this product for knee pain experienced rapid weight gain and facial puffiness after several months of use. She was subsequently diagnosed with diabetes and Cushing’s syndrome. [https://tinyurl.com/28boz2ko]
Two products labelled as “100% vegetarian” or “100% herbal” were found to contain six adulterants, including dexamethasone. One was linked to the development of Cushing’s syndrome in a man in his 60s who used the product for psoriasis for 3–4 months. Another was associated with steroid-induced Cushing’s syndrome in a woman in her 50s who used the product for 3–4 months to treat her headache. [https://tinyurl.com/28l9wcvq; https://tinyurl.com/25meun94]
A product marketed for weight loss was found to contain sibutramine levels at twice the previously permitted maximum daily dose. Its use resulted in tachycardia, breathlessness, and dizziness in a woman in her 40s. A more serious case occurred in a woman in her 50s who experienced ventricular tachycardia, leading to unconsciousness, and required emergency resuscitation after using an adulterated slimming product for 3 months. Her treatment required defibrillator implantation and long-term heart failure medication. [https://tinyurl.com/254ofuq3; https://tinyurl.com/24rnbnb8]
Regulatory, patient safety implications
“These findings carry important regulatory and patient safety implications. From a regulatory standpoint, they reinforce the need for robust postmarketing surveillance, including targeted laboratory testing of CHPs, particularly those marketed for pain relief and anti-inflammatory purposes,” the investigators said.
“From a patient safety perspective, healthcare professionals should routinely enquire about CHP use during clinical assessments and should maintain a high index of suspicion for undeclared drug adulteration when patients present with unexpected clinical findings after consuming CHPs,” they added.
The use of CHPs has become increasingly prevalent in Singapore, given its widespread availability through pharmacies, health stores, and online platforms. Products touted as “natural” may be perceived as inherently safe by consumers, leading to prolonged use or concurrent use with multiple products without professional guidance. [J Pharm Policy Pract 2023;16:134; Cureus 2022;14:e26893]
It is all the more important for the public to be educated about the risks of unregulated CHPs and for healthcare professionals to report AEs whenever an association with a CHP is suspected, according to the investigators.
AE reports in detail
The 727 AE reports associated with CHPs accounted for 0.4 percent of all reported AEs submitted to the HAS over the 7-year period. These reports were mostly concentrated among women (63.1 percent), older adults (≥60 years: 40.9 percent), and the Chinese (59.6 percent). The main source of AE reports were doctors (89.9 percent) and public hospitals and polyclinics (86.9 percent).
Of the 160 reports with documented indications for CHP usage, 33.1 percent pertained to CHPs used for pain relief, 20.6 percent for general health and wellbeing, and 8.8 percent for weight management. Other indications included skin conditions, cough, diabetes, hypertension, liver health, and sexual performance enhancement.
When classified according to system organ class, 432 reports involved “skin and appendages disorders” (ie, rash, pruritus, angioedema, urticarial, periorbital oedema), 91 reports involved “body as a whole – general disorders” (ie, pain, oedema, fever, anaphylactic reaction, and malaise), 57 reports concerned “liver and biliary system disorders,” and 42 reports entailed “endocrine disorders.”
Most reports (65 percent) classified under “skin and appendages disorders” were attributed to glucosamine-containing products. Meanwhile, “body as a whole – general disorders,” “liver and biliary system disorders,” and “endocrine disorders” reports were largely linked to products adulterated with undeclared drugs.