Increased oversight is urgently needed regarding the caffeine content in pre-workout supplements, which are growing in popularity and which often contain harmful amounts of the ingredient, writes a team of experts from the University of Cape Town in the SA Medical Journal.
In a letter to the SAMJ editor, J Taylor, G Tatz, N Madikizela and M Blockman write:
We are concerned about methylxanthine-mediated toxicity associated with multi-ingredient pre-workout supplements (MIPS) in South Africa. Marketed as exercise performance enhancers, these are often sold as proprietary blends with incompletely disclosed ingredients, and frequently contain stimulants such as caffeine and theobromine.
Labelling inaccuracy was highlighted in an Australian study, in which measured caffeine ranged from 59% to 178% of the labelled amount, with significant variability between product batches. This raises concerns for dose-dependent and additive toxicity. Recently, an adult presented to the emergency unit with a sympathomimetic toxidrome after ingestion of a MIPS and an energy drink – with chest pain, palpitations, difficulty breathing and vomiting, consistent with methylxanthine toxicity.
Examination findings included diaphoresis, sinus tachycardia, mild hypertension and bilateral mydriasis. There was no history of prescription or illicit drug use. Urine toxicology was negative for amphetamines and cocaine. Supportive care with intravenous fluids and benzodiazepines led to complete resolution of the presenting symptoms.
Caffeine, and other methylxanthines, produce sympathomimetic-like toxicity, although gastrointestinal effects are more prominent. Toxicity includes vomiting, central nervous system stimulation (e.g, tremor, agitation), tachypnoea, sinus tachycardia and hypokalaemia.
Severe toxicity may result in arrhythmias, seizures and rhabdomyolysis. Case reports and case studies have showcased the harms associated with caffeine toxicity from MIPS. This case highlights the importance of a detailed supplement history and high index of suspicion for MIPS-related toxicity in patients presenting with sympathetic over-activity.
Furthermore, it underscores a critical regulatory gap in SA. Caffeine intended for injection is a schedule 3 medicine, subject to full regulatory oversight by the SA Health Products Regulatory Authority (SAHPRA). Caffeine, only as part of multiple substance formulations, is also permitted under SAHPRA’s Category D complementary medicines and health supplements guidance, subject to a maximum daily dose of 300 mg.
Despite this, manufacturers of MIPS that contain caffeine may position these products as foodstuffs, placing them outside SAHPRA’s rigorous regulatory processes.
Healthcare workers and consumers should be alerted to the unregulated nature of these products and the risks of harm, especially when co-ingesting multiple caffeinated products.
Their increasing popularity and availability obligates enhanced regulatory oversight.
J Taylor; G Tatz; N Madikizela; M Blockman – Division of Clinical Pharmacology, Department of Medicine, University of Cape Town.
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