State (situational) anxiety can create suboptimal outcomes for patients across a variety of health care specializations. While anxiolytic medications reduce anxiety, problematic side effects can compromise outcomes. These challenges have spurred searches for nonpharmaceutical approaches to alleviate patient anxiety. This systematic literature review, largely following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, aimed to determine patterns and effectiveness of interventions across medical health care specialty areas, including dentistry. A systematic review was conducted, using PubMed, CINAHL, and PsycINFO databases, with search terms related to anxiety, specific interventions, and medical or dental procedures. Hand searching for additional citations was performed on the bibliographies of dissertations, meta-analyses, and systematic reviews that met article inclusion criteria. The search process yielded 48,324 articles and 257 dissertations published in English between 1974 and 2018. Each abstract was evaluated for inclusion by two reviewers, yielding 718 articles that were read and evaluated for outcomes, risk of bias, pretest and post-test, controls and quality, using a Critical Appraisal Skills Programme instrument. Of these, 408 articles, describing 501 experimental trials, were accepted for inclusion in this analysis. A total of 50,343 patients were included in these experiments, with an overall success rate of 71% for reducing patient anxiety. Results are summarized by health care specialty area: surgery, oncology, cardiology, obstetrics/gynecology, dentistry, and pain/trauma, and the following diagnostic testing and intervention areas: imaging, colonoscopy, mechanical ventilation, and other. The largest number of experiments (114) was in the surgery category. The types of interventions included , , , , , , , , , , , , , and . The largest numbers of experiments were done with (143) and (130). The following interventions were most successful, reducing anxiety in over 70% of experiments: , , , , , , Confidence in results is limited by publication bias, small sample sizes, and the lack of placebo controls. Directions for future research are discussed.