•OHCs enable physicians to share both general and specific health knowledge.•General knowledge-sharing is positively associated with specific knowledge-sharing through online reputation.•Patient involvement strengthens the effects of general knowledge-sharing on online reputation and specific knowledge-sharing.•General knowledge-sharing can be an efficient approach for physicians to recruiting patients. Although the sharing of knowledge in online health communities (OHCs) has been explored in recent years, little research has been done to explore the relationship between general and specific knowledge-sharing. Based on the literature on knowledge-sharing in OHCs, this study developed a research model to explore how physicians’ general knowledge-sharing behaviors influence their specific knowledge-sharing activities via their online reputations and the contingent role of patient involvement in OHCs. The research model was tested using objective data from a leading OHC in China. The results show that general knowledge-sharing is positively associated with specific knowledge-sharing, and this effect is exerted through online reputation. Moreover, patient involvement strengthens the relationship between general and specific knowledge-sharing as well as the relationship between online reputation and specific knowledge-sharing. By uncovering the relationship between general and specific knowledge-sharing, the research findings extend the understanding of knowledge-sharing and patient recruiting in OHCs and provide significant practical implications for practitioners.