$Objective:$ To identify barriers and facilitators of medication adherence in patients with stroke along with their caregivers. DESIGN: Qualitative thematic analysis of posts about secondary prevention medications, informed by Perceptions and Practicalities Approach.

$Setting:$ Posts written by the UK stroke survivors and their family members taking part in the online forum of the Stroke Association, between 2004 and 2011.

$Participants:$ 84 participants: 49 stroke survivors, 33 caregivers, 2 not stated, identified using the keywords 'taking medication', 'pills', 'size', 'side-effects', 'routine', 'blister' as well as secondary prevention medication terms.

$Results:$ Perceptions reducing the motivation to adhere included dealing with medication side effects, questioning doctors' prescribing practices and negative publicity about medications, especially in regard to statins. Caregivers faced difficulties with ensuring medications were taken while respecting the patient's decisions not to take tablets. They struggled in their role as advocates of patient's needs with healthcare professionals. Not experiencing side effects, attributing importance to medications, positive personal experiences of taking tablets and obtaining modification of treatment to manage side effects were facilitators of adherence. Key practical barriers included difficulties with swallowing tablets, dealing with the burden of treatment and drug cost. Using medication storage devices, following routines and getting help with medications from caregivers were important facilitators of adherence.

$Conclusions:$ An online stroke forum is a novel and valuable resource to investigate use of secondary prevention medications. Analysis of this forum highlighted significant barriers and facilitators of medication adherence faced by stroke survivors and their caregivers. Addressing perceptual and practical barriers highlighted here can inform the development of future interventions aimed at improving adherence to secondary prevention medication after stroke.