While some reports have found that some people with clinical depression can experience unpredictable effects, other people with depression have reported major benefits from regular floating. You are advised to discuss floatation with your clinician and carefully consider his or her advice.
Obviously patients with open wounds or incontinence are unsuitable candidates. Patients with severe hypertension may experience such drastic reduction in blood pressure as to faint but when this is controlled by a drug regime, there is little risk. Similarly there is little risk for controlled epileptic patients, but it is recommended to have a suitable helper present during the float session.
Floating under the influence of narcotics or soporifics or indeed any drug affecting consciousness is strongly opposed because deep sleep can result.