Introduction Tension-type headache (TTH) is the most prevalent neurological disease, with an estimated 1.5 billion cases worldwide. Pharmacotherapy should be considered by patients with TTH who have a limited response to non-pharmacological treatment. However, recommendations for the vast array of therapeutic drugs for TTH partially overlap, with conflicting recommendations for strength in different guidelines; these may confuse the decision-making process of clinicians. Hence, the aims of this study are to analyse the available direct and indirect evidence on different drug monotherapies for TTH in adults, and to generate a treatment ranking according to their efficacy and safety outcomes by using a Bayesian network meta-analysis (NMA). Methods and analysis We will systematically search the Cochrane Library, PubMed, Web of Science, Embase, China Biomedical Literature Database, International Clinical Trials Registry Platform and other resources for eligible studies. Randomised controlled trials on different drug monotherapies for TTH will be included. Two review authors (RX and YW) will independently search and select the studies, extract the data and assess the risk of bias. A Bayesian NMA will afterwards be conducted to pool the effect measures across all types of monotherapy drugs. The ranking probabilities of the efficacy and safety of different drug monotherapies will be estimated. Heterogeneity will be quantified using the Q statistic and the I-2 index. Inconsistency between direct and indirect evidence will be assessed by the node-splitting model. In addition, the overall quality of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. Ethics and dissemination No ethical issues are foreseen. The results will be published in a peer-reviewed journal, which will be disseminated electronically and in print.