Khat is a psycho stimulant herb, which has been in use in traditional societies in East Africa and the Middle East over many centuries. Although khat is reported to cause various health problems, what constitutes problematic khat use has never been systematically investigated. This study explored the acceptable and problematic uses of khat from the perspective of users. The study used an exploratory sequential design in which qualitative (emic) data was collected to define problematic khat use and quantitative data was then collected to evaluate the utility of the framework developed through the qualitative approach. The qualitative data was gathered through in-depth interviews (N=11) and focus group discussions (N=26). By supplementing this emic exploration of the experiences considered to constitute problematic khat use with an etic definition, DSM-5 criteria for stimulant related disorders, a structured questionnaire was developed. Then the quantitative study consisted of a cross-sectional evaluation of 102 respondents was done. Respondents both for qualitative and quantitative study were selected through snowballing and convenience sampling methods. Qualitative data were transcribed and subjected to thematic analysis whereas quantitative data were analyzed using descriptive statistics and nonparametric statistics. Impaired control, social and occupational impairment, recurrent risky sexual engagement after chewing khat, craving (harara), hazardous use, diminished effect (wesewase) and withdrawal sign/symptoms of khat were defined by the respondents as a criteria for problematic khat use. Frequency of chewiwng khat; three or four times per month unlike socio demographic characteristics of respondents was the independent predictor of problematic khat use [OR, 95% CI; 16.9(1.31, 21.7)]. Problematic khat use was also significantly associated with amount of khat, X2 (10,101) =19.82, p = .03, Cramer’s = .48 and problem drinking X2= (1,100) = 7.82, p = .005, phi = .3. Problematic khat use had also a negative impact on psychological wellbeing and alcohol use behavior. The study demonstrates that problematic khat use can be defined and evaluated. Interestingly there was a major overlap between the emic and etic approaches although the list of indicators for problematic use was more extensive in the emic approach. The study may form the basis for further exploration of the distribution of problematic khat among khat users.