Turkey has been among the leading countries in antibiotic consumption. As a result of the 4-year National Action Plan for Rational Drug Use, antibiotic prescriptions had declined from 34.9% in 2011 to 24.6% in 2018. However, self-medication with antibiotics without prescription is common, which is not reflected in official statistics. The present study aims at investigating antibiotic use in the community and the factors related to it. A web-based survey was conducted among 945 Turkish-speaking respondents (61.3% female). The questionnaire included questions about antibiotic use for different illnesses, ways to obtain and handle leftover antibiotics, knowledge, beliefs of the antibiotic effectiveness, attitudes, health anxiety, and background factors. According to the results, 34.2% of the sample had self-medicated themselves with antibiotics without a valid prescription. The most common way to self-medicate was to use leftover antibiotics. While 80.4% knew that antibiotics are used to treat bacterial infections, 51.4% thought that antibiotics are effective for viral diseases. The most important predictor of antibiotic use frequency was the belief in their efficiency for various illnesses and symptoms, followed by negative attitudes to antibiotics, health anxiety, knowledge level, positive attitudes, and health status. The results underline the importance of targeting misbeliefs about antibiotics in future campaigns.