This study determined how hypnosis and empathic attention during percutaneous tumour treatments affect pain, anxiety, drug use and adverse events. For their tumour embolisation or radiofrequency ablation, 201 patients were randomised to receive standard care, empathic attention with defined behaviours displayed by an additional provider, or self-hypnotic relaxation including the defined empathic attention behaviours. All had local anaesthesia and access to intravenous medication. Main outcome measures were pain and anxiety assessed every 15 min by patient self-report, medication use (with 50 μg fentanyl or 1 mg midazolam counted as one unit), and adverse events, defined as occurrences requiring extra medical attention, including systolic blood pressure fluctuations (≥50 mmHg change to >180 mmHg or <105 mmHg), vasovagal episodes, cardiac events, and respiratory impairment. Patients treated with hypnosis experienced significantly less pain and anxiety than those in the standard care and empathy groups at several time intervals and received significantly fewer median drug units [mean 2.0; interquartile range (IQR) 1–4] than patients in the standard and empathy groups. Thirty-one of 65 patients (48%) in the empathy group had adverse events, which was significantly more than in the hypnosis group and standard care group.