Clinicians warn of dangers linked to pre-workout supplements

Clinicians from the University of Cape Town (UCT) are warning about potential dangers in pre-workout supplements in a new study.

An adult patient who recently presented to the emergency unit with chest pain, a racing heart and difficulty breathing after consuming a pre-workout supplement and an energy drink has prompted clinicians to call for tighter oversight of a fast-growing but lightly regulated market. Popular among gym-goers and athletes, many of these supplements are sold as proprietary blends that do not fully disclose all their ingredients.

The warning, published in the South African Medical Journal, comes from clinicians in UCT’s Division of Clinical Pharmacology, who are calling for healthcare professionals and consumers to be more aware of the risks associated with multi-ingredient pre-workout supplements (MIPS), products widely marketed to boost exercise performance.

 “This case demonstrates the importance of asking patients about supplement use when they present with symptoms of stimulant toxicity. Many people assume these products are safe because they are readily available, yet their ingredients and stimulant content are not always fully disclosed,” said Professor Marc Blockman, director of the World Health Organization Collaborating Centre for Medicines Information at UCT.

Regulatory oversight

The case illustrates how easily consumers may unknowingly ingest potentially harmful amounts of stimulants. The supplements frequently contain methylxanthine stimulants, such as caffeine and theobromine, and international studies have shown that the actual caffeine content in such products can differ substantially from what is stated on the label.

“Stronger regulatory oversight is needed to ensure consumers know what they are taking.”

According to Professor Blockman, caffeine and related methylxanthines stimulate the central nervous system and cardiovascular system. Mild toxicity can cause vomiting, tremors, agitation, rapid breathing and a racing heartbeat, while severe poisoning may lead to abnormal heart rhythms, seizures and muscle breakdown.

He said that there is a significant regulatory gap in South Africa. While injectable caffeine is regulated as a Schedule 3 medicine by the South African Health Products Regulatory Authority, manufacturers may market caffeine-containing pre-workout supplements as food products, placing them outside many of the stringent regulatory requirements that apply to medicines.

Blockman added: “As the use of pre-workout supplements continues to increase, stronger regulatory oversight is needed to ensure consumers know what they are taking and to minimise the risk of avoidable toxicity. Greater transparency around ingredients and stimulant content would help both consumers and healthcare professionals make informed decisions.”