Patients who are involved in health communication are expected to have a better lifestyle to achieve a higher health status. Effective communication can produce a common understanding as well as an attitude improvement. Thus pharmaceutical personnel must have the ability to communicate effectively. This study aims to determine the factors that affecting the effectiveness of communication in providing drug information. The research was carried out using a semi-structured interview method. The data were analyzed using the Interpretative Phenomenological Analysis (IPA) method. Seven pharmacy technicians and ten pharmacists join the study. Several research themes can influence the effectiveness of communication between pharmacists and patients, including pharmacist empathy, pharmacist reliability and responsiveness, pharmacy atmosphere, patient empathy, patient physical and mental state, patient competency, and patient feedback. Several sub-themes were found which could be facilitators and barriers to effective communication. Based on the Shannon-Weaver communication model, these factors can affect the message encoding process, the information delivery channel, the message decoding process, and the feedback delivery process. Effective communication is influenced both by pharmacists as information providers and patients as recipients of drug information, the pharmacy environment can influence communication channels. Interventions to create effective communication should not only be given to pharmacists but also aimed at patients and the pharmacy environment.