Access to essential medicines is a critical health issue in many developing countries, including Nigeria, where urban poverty exacerbates this challenge. Mobile payment systems have emerged as innovative solutions to improve access and affordability of these medicines among low-income populations. The study employs a combination of quantitative surveys and qualitative interviews to gather data from 1000 participants randomly selected from the urban poor population in Lagos. Quantitative data will be analysed using logistic regression models to assess the impact of mobile payments on medication adherence. Qualitative insights will be synthesized through thematic analysis. Mobile payment systems have significantly increased medication utilization among the study's participants, with a reported 85% indicating that they use these systems for purchasing essential medicines. However, adherence rates remain below optimal levels, particularly among those who face financial constraints or lack understanding of proper dosing. While mobile payments offer substantial benefits in increasing access to medications, there is still room for improvement in enhancing patient education and support mechanisms to improve overall health outcomes. Healthcare providers should integrate more educational resources into their services, especially targeting the urban poor. Policymakers should consider subsidizing or incentivizing mobile payment systems further to ensure equitable distribution of essential medicines. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.