Does the Wim Hof Method really work?

Research into the Wim Hof Method (WHM) covers breathing exercises, cold exposure and mindfulness. The strongest evidence comes from small but randomised studies in specific patient groups. In 25 MS patients who followed the WHM for 12 weeks, cognition, fatigue, anxiety and depression improved significantly compared with a control group. In 24 patients with a chronic joint inflammation (axial spondyloarthritis), inflammatory markers fell after 8 weeks of WHM. These are not large trials, but they are randomised and found measurable effects.

In healthy women with high levels of stress, depressive symptoms fell after 3 weeks of WHM by as much as they did after meditation, HIIT or other breathing techniques. WHM therefore did not perform better than the alternatives, which suggests that it may be the movement, relaxation or attention that helps, rather than something unique to the method itself. Only after 3 months did a smaller subgroup that had stuck closely to the method show slightly better results, but this was not a pre-planned part of the study.

A randomised study in people with a spinal cord injury is still ongoing, but results are not yet available.

One point that should be taken seriously is the safety of the cold element. Repeatedly inhaling cold, dry air during exercise demonstrably damages the airways: lung function declines and a blood marker of airway damage rises sharply. People with asthma or other respiratory conditions should be cautious here. Serious adverse effects from the intervention itself did not occur in the small patient studies, but the studies are too small to detect rare side effects.