monotherapies

Monotherapy is a medical treatment approach in which a single therapeutic agent or modality is used to treat a disease or condition, rather than combining multiple agents or modalities. It is commonly contrasted with combination therapy, where two or more treatments are used together. Monotherapy can refer to pharmacologic therapy with one drug, a single nonpharmacologic modality such as radiotherapy or psychotherapy, or a regimen that relies on one line of therapy.

Contexts and examples vary by field. In pharmacology, initiating treatment with one drug is common, such as metformin for type 2 diabetes or an antidepressant for mild to moderate depression. In oncology, single-agent chemotherapy is used in certain situations, such as for frail patients or early-stage disease. In infectious diseases, monotherapy may be appropriate for some infections but is often avoided for others due to concerns about resistance and effectiveness. In psychiatry, monotherapy with a single class of medication is standard in many guidelines, though augmentation or combination strategies are employed when response is inadequate.

Advantages of monotherapy include simpler regimens, easier adherence, reduced risk of drug–drug interactions, simpler monitoring, and lower cost. Disadvantages include the potential for insufficient efficacy in complex or advanced disease, slower or weaker response, and a higher risk of treatment failure if the condition is resistant or multifactorial. The choice between monotherapy and combination therapy depends on disease characteristics, patient factors, and evidence-based guidelines.