Inclusion Criteria:  (i) Either much bothered by at least one somatic symptom (2 points on at least one item of the PHQ-15) or at least a moderate overall somatic symptom burden (PHQ-15 sum ≥10), with (ii) recurrent distress related to somatic symptoms ≥4 months Interested in completing an intense psychological treatment with the aim of reducing distress associated with physical symptoms Adult (≥18 years old) Living in Stockholm County Can read and write in Swedish Complete baseline assessment  Exclusion Criteria:  Symptoms best explained by, or clinical picture dominated by, severe health anxiety or a non-somatoform psychiatric disorder such as depression, panic disorder, primary insomnia, a chronic stress disorder, or an acute stress disorder Severe psychiatric condition or suicidal ideation Clear medical risk in taking part in exposure-based treatment (e.g., pregnancy) or somatic condition (e.g., recent cancer diagnosis), or treatment for somatic condition (e.g., recent chemotherapy), makes treatment unfeasible Continuous psychotropic medication (antidepressants, anticonvulsants, mood-stabilizers, antipsychotics) not stable in past 4 weeks, or not expected to remain stable over the main phase of the trial Severe alcohol or substance use disorder likely to interfere with treatment Planned absence for more than 1 week during the intended main phase