Objectives: While prior studies showed the associations between inadequate health literacy (HL) and poor medication-related skills, this study aimed to identify medication related health instruments, compare the dimensions of HL within these instruments and identify the types of medication information that can be gleaned from them.

Methods: Three databases (i.e., PubMed, Scopus, and EMBASE) and hand-searching for original studies or systematic reviews were used to find studies about medication-related HL measures published between 2000 and 2018. The standardized operation procedures following the PRISMA were implemented to systematically search the literature, assess the validity and reliability of instruments, extract the required information of HL dimension and type of information necessary for optimal and safe use of medication (type of medication information necessary) and compared accordingly.

Results: Of 6,104 available records, 48 instruments were identified from 44 studies. Thirty-one studies had 33 instruments (68.8%) which were either disease-specific or medication-specific HL studies. The majority of instruments with diverse sample sizes showed a certain extent of reliability and validity. The proportions of HL dimension and types of medication information varied across different types of studies. For medication-specific studies, comprehension and evaluation were the major dimensions of HL while dosing information and treatment indication were the main types of medication information reported. Of five instruments most appropriate for medication-related HL, four of them were from disease-specific or medication-specific studies. These instruments consistently covered the dimensions of literacy and comprehension, as well as medication-related information regarding dosing, treatment indication, and side effects/precautions.

Conclusion: Only disease- or medication-specific studies tended to develop medication-related HL instruments. Hence, there is no consensus yet on how to capture the specific dimensions of HL or types of medication information. Of five instruments identified as the better options to measure medication-related HL, HL dimensions (comprehension and evaluation), and medication information about dosing, treatment indication, and side effects were commonly covered in these instruments. Further studies are needed to confirm the required HL dimensions and medication information.