Triathlon’s popularity is rapidly increasing, and epidemiological data relating to its related medical conditions is crucial to the development of proper medical plans and safety guidelines for it. This study examined the data from the medical reports collected during three consecutive editions of Ironman Italy, from 2017 to 2019. Out of 10,653 race-starters, 3.3% required medical attention sustaining 472 medical conditions. A significantly higher injury risk was found for females versus males (χ2 = 9.78, p = 0.02) and in long-distance (IR: 4.09/1,000hours) rather than in Olympic/middle distance races (IR: 1.75/1,000hours). Most (68.4%) conditions (including muscular exhaustion, hypothermia, and dehydration) were systemic, whilst only 10.2% were acute traumatic injuries. Of a total of 357 triathletes requiring medical assistance, 8.1% were a candidate for hospitalisation. The equipment and personnel that are required for the medical assistance in future triathlon events were estimated based on Maurer’s algorithm, and ten practical recommendations for triathlon medical support were formulated.

• Race formats were risk ordered by distance, with long-distance exhibiting higher risk than Olympic and middle distance courses.

• Most acute and overuse injuries involving the musculoskeletal system were localised to the lower limbs, and most were minor injuries including abrasions, contusions, ankle sprain, muscle strain, muscle cramps and plantar fasciitis.

• An advanced medical facility should be located near the start/finish line and a smaller one on the beach.

• For medium to long-distance race series, the presence of two doctors should be recommended.

• A portable ultrasound scanner may allow the execution of FAST examination and thoracic ultrasound, confirming many clinical conditions quickly, with the related medico-legal benefits.