What does cytotoxic mean?
Cytotoxic is an adjective meaning toxic to cells — describing any substance, drug, or agent capable of killing or damaging them. The term belongs primarily to medicine and biology: most famously, it describes the chemotherapy drugs that destroy rapidly dividing cancer cells, though such agents cannot perfectly distinguish tumor cells from healthy ones, which accounts for many side effects of cancer treatment. Cytotoxic also applies within the immune system, where cytotoxic T cells are specialized white blood cells that identify and eliminate virus-infected or malignant cells. Related forms include cytotoxicity (the degree to which something harms cells) and cytotoxin (a toxin that acts on cells), and the term should not be confused with cytostatic, which refers to agents that halt cell division without necessarily killing cells. Understanding cytotoxic offers a window into how modern medicine fights disease at the level of individual cells — both harnessing cell death as a weapon against cancer and guarding against collateral damage to healthy tissue.
adjectiveToxic to cells; having the property of killing or damaging cells, especially living cells such as bacteria or tumor cells.
- (Of a substance, drug, or agent) toxic to cells; capable of killing or damaging cells, especially used of anticancer drugs and chemicals.
- (Of cells, especially T lymphocytes) able to destroy other cells, as in cytotoxic T cells of the immune system.
"Chemotherapy works by delivering cytotoxic drugs that destroy rapidly dividing cancer cells."
"Patients undergoing cytotoxic therapy are monitored closely for damage to healthy tissue."
"Cytotoxic T lymphocytes recognize and eliminate virus-infected cells."
Your immune system carries an army of cytotoxic T cells — killer cells literally trained to hunt down and destroy your own infected or cancerous cells one by one.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cytotoxic
The word cytotoxic combines two Greek-derived elements: 'cyto-', from Greek 'kytos' meaning hollow vessel or cell, and '-toxic', from Greek 'toxikon', originally referring to poison for arrows. It emerged as a scientific compound in the late nineteenth and early twentieth centuries alongside the rise of cytology and cellular pathology. Its sibling terms — cytoplasm, cytology, cytokine, toxin, and toxicity — share the same classical roots, reflecting the Greek vocabulary that underpins much of modern biomedical terminology.
Related word forms
How cytotoxic is actually used
A technical term used chiefly in medicine, pharmacology, oncology, and immunology. In everyday medical contexts it is most often encountered in relation to chemotherapy, where 'cytotoxic' is sometimes used informally (and slightly imprecisely) to refer to the treatment itself rather than the drugs.
Easily confused with cytotoxic
Cytotoxic substances kill cells outright, while cytostatic substances merely inhibit or slow cell division without destroying the cells.