What does dosology mean?
Dosology is the branch of medical science concerned with determining the correct doses of medicines — how much of a drug should be administered, to whom, and how often. Also known by the more common term posology, it sits at the heart of safe prescribing: factors such as a patient's age, body weight, organ function, and disease state all shape the dose that is both effective and non-toxic. The word derives from the Greek "dosis", meaning a giving or portion, combined with the suffix "-logy", denoting a field of study. Though largely confined today to technical and historical medical writing, dosology captures an idea with life-or-death stakes: the difference between a remedy and a poison frequently lies only in quantity. For readers encountering it in older texts or pharmacological discussions, understanding dosology means recognising the systematic effort to replace guesswork with precision in medicine.
nounThe branch of medical science concerned with the determination of proper doses of medicines; the study of dosage.
- The branch of pharmacology dealing with the determination and administration of appropriate doses of medicines (also called posology).
"Accurate dosology is essential when prescribing drugs for infants, whose tolerance differs markedly from that of adults."
"Modern dosology draws on patient weight, age, kidney function, and genetics to tailor safe medication amounts."
"The textbook's chapter on dosology explained how paediatric doses are scaled down from adult standards."
Before dosology existed as a discipline, physicians often guessed at medicine quantities by eye — one reason historical remedies could cure or kill in nearly identical amounts.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dosology
Dosology comes from the Greek "dosis" (a giving, a portion, hence a measured amount of medicine) plus "-ology", from Greek "logos" (study or discourse). It entered English in the nineteenth century alongside other medical compound terms ending in -ology. It shares its root with "dose" and "dosage" and is essentially synonymous with "posology", which was built from the same Greek elements and remains the preferred term in modern pharmacology.
How dosology is actually used
A rare, technical term found chiefly in older or specialist medical literature. In contemporary clinical practice, "posology" is the more usual term, and everyday contexts simply use "dosing" or "dosage". Dosology carries a formal, scholarly register.
Easily confused with dosology
Posology is the more common term for the study of drug dosages, while dosology is a rarer synonym; neither should be confused with dosimetry, which concerns measuring radiation doses.
Dosimetry is the measurement of absorbed doses of radiation, whereas dosology concerns medicinal doses of drugs.