Chemical intolerance (CI), in clinical settings often referred to as Multiple chemical sensitivity (MCS), is a condition characterized by adverse reactions to low-level chemical exposures considered non-harmful for the general population. Here we present results from a multiple case-study where we aimed to evaluate the effects of a novel exposure-based intervention for alleviating CI symptoms. Five women underwent repeated, well-controlled exposure to a symptom-eliciting stimulus (n-butanol) in a laboratory setting across five weeks. The main outcome included ratings of symptom intensity following exposure. The results showed consistent reductions in ratings of symptom intensity pre to post intervention, indicating increased tolerance. Further, effects persisted at the six-month follow-up. Treatment adherence was high among all participants. These findings suggest that well-controlled and individualized exposure may be a viable treatment avenue for CI, which is a prevalent condition with limited or no treatment alternatives. Study limitations include the restricted generalizability following a multiple case-study and the limited scalability of the treatment setting.