Online health communities provide a rich source of expertise from experienced patients, but uncovering 'peer mentors' with shared circumstances is like finding a needle in a haystack—a problem that will escalate as these communities grow and diversify. We investigated interactive health interest profiles (HIPs) that summarize health-related terms extracted from users' community posts. Through iterative design, we explored practical designs that accommodate differences in users' community participation in three HIP prototypes: Text, Word Cloud, and Timeline. By comparing prototype usability with patients and design experts, we found that patients accurately used each prototype but completed some tasks faster with the Timeline HIP. Despite this advantage, patients preferred the Text HIP. Design experts and patients agreed that simple data overviews and granular details with salient cues that invite interactivity are key design considerations for HIPs. Findings offer key design considerations for HIPs that patients find most useful when forging critical connections.