Does homeopathy have anything to contribute to hormesis?

Homeopathy is the best known medical analogue of hormesis, others include hormoligosis and paradoxical pharmacology. Homeopathy is based on the concept Similia similibus curentur ('Let like be cured by like'); the exploitation of secondary effects of drugs, the body's reaction rather than the primary pharmacological action. The most controversial aspect of homeopathy is its use of 'ultramolecular' dilutions in which a single molecule of the starting substance is unlikely to be present. Classical pharmacological actions in vivo have been reported with dilutions as high as 10(-22)mol/L, but homeopathic medicines may be far more dilute than this. There is growing biological evidence including independent reproduction that in vivo effects may occur at such dilutions. In a systematic review, 73% of experiments showed an effect with ultramolecular dilutions including 68% of high-quality experiments. Physical and physico-chemical work suggests that homeopathic preparations contain stable ordered supramolecular structures, gas nanobubbles and dissolved silicates may be involved. Homeopathy may contribute to the generalizability and reproducibility of hormesis effects. It also raises the question of the threshold of hormesis effects.