Background: As people age, they become increasingly vulnerable to the untoward effects of medicines due to changes in body systems. These may result in medicines related problems (MRPs) and consequent decline or deterioration in health. Aim: To identify MRPs, indicators of deterioration associated with these MRPs, and preventative interventions from the literature. Design and Setting: Systematic review of primary studies on MRPs originating in Primary Care in older people. Methods: Relevant studies published between 2001 and April 2018 were obtained from Medline (via PubMed), CINAHL, Embase, Psych Info, PASCAL, Scopus, Cochrane Library, Science Direct, and Zetoc. Falls, delirium, pressure ulcer, hospitalization, use of health services and death were agreed indicators of deterioration. The methodological quality of included studies was assessed using the Down and Black tool. Results: There were 1858 articles retrieved from the data bases. Out of these, 21 full text articles met inclusion criteria for the review. MRPs identified were medication error, potentially inappropriate medicines, adverse drug reaction and non-adherence. These were associated with indicators of deterioration. Interventions that involved doctors, pharmacists and patients in planning and implementation yielded benefits in halting MRPs. Conclusion: This Systematic review summarizes MRPs and associated indicators of deterioration. Appropriate interventions appeared to be effective against certain MRPs and their consequences. Further studies to explore deterioration presented in this systematic review is imperative.