Background: Whether pharmacists should sell complementary medicines that lack evidence of effectiveness is an important ethical question which is not explicitly addressed in the existing literature or professional guidelines. The question arises because many complementary medicines lack rigorous evidence that they are effective. There is a need for specific practical guidance for pharmacists regarding their responsibilities when selling complementary medicines. Objective: Outline and defend an ethical framework for the responsibilities of pharmacists when selling complementary medicines. Method: Principle-based ethics consists in the application of the four bioethical principles to make decisions in healthcare. A public health argument is provided that supports the sale of complementary medicines in pharmacy providing pharmacists meet a number of specific professional responsibilities. The theoretical resources provided by principle-based ethics are used to develop and defend a framework for the responsibilities of pharmacists when selling complementary medicines. The proposed framework is defended against counter-arguments that propose a stricter or more lenient approach. Results: The framework identifies the following responsibilities of pharmacists selling complementary medicines: (1) pharmacists should provide evidence-based recommendations to consumers regarding complementary medicines, (2) pharmacists should train all staff in a pharmacy to ensure that they provide evidence-based recommendations regarding complementary medicines and refer to a pharmacist when required, (3) when providing advice, pharmacists should provide sufficient information for consumers to make informed decisions, (4) pharmacists should setup the pharmacy so that consumers are offered advice from a pharmacist when purchasing complementary medicines; pharmacists need to be available to provide that advice, and (5) pharmacists must be vigilant for complementary medicine harm and intervene if risk of harm is significant. Conclusion: The framework provides practical guidance for pharmacists regarding their responsibilities when selling complementary medicines.