Definition of placebo in US English:



  • 1A harmless pill, medicine, or procedure prescribed more for the psychological benefit to the patient than for any physiological effect.

    ‘his Aunt Beatrice had been kept alive on sympathy and placebos for thirty years’
    as modifier ‘placebo drugs’
    • ‘According to the report published in the British Medical Journal, 60 percent of medical professionals prescribe placebos to their patients.’
    • ‘Most doctors are aware of placebos and the placebo effect, but probably few have given the subject any serious thought.’
    • ‘Patients could also be prescribed a placebo as part of this research, but the nutrition and exercise counseling is worth a lot on its own.’
    • ‘In light of this finding, it seems likely that the many such practitioners will continue to prescribe placebos.’
    • ‘The test, conducted in London by four general practices and a hospital ear, nose and throat outpatient department, studied the effects of homeopathic remedies versus placebos on 50 patients with allergic rhinitis.’
    • ‘According to a new study by Israeli researchers, most doctors prescribe placebos to their patients, and in most of these cases, the patients are told they are receiving real medication.’
    • ‘The point is that all therapeutic practices, all therapeutic interactions have a placebo component.’
    • ‘All patients received placebo via the inhaler and were instructed on the proper technique for using this device.’
    • ‘If there is no existing treatment, a placebo might be used (a placebo is a treatment that has no physical effect).’
    • ‘For a long time, medical practitioners have believed that placebos have therapeutic value.’
    • ‘Traditional Chinese medicines are basically placebos and when they do seem to work it is largely due to the illegal insertion of potent western medicines such as steroids.’
    • ‘This requirement may conflict with the Declaration of Helsinki, which deems it unethical to give patients a placebo if an evidence based treatment is available.’
    • ‘A major gap is apparent in the literature examining patient understanding of placebos and their effect.’
    • ‘And, if some patients benefit from placebos, and they are not harmed, I guess I can live with that.’
    • ‘A practitioner who administers a placebo wants to benefit the patient by making the patient believe that he is receiving an active treatment.’
    • ‘Sensitivity analysis excluding those patients who received the placebo tablet did not change our conclusions.’
    • ‘The placebo effect is then defined as the difference in effect in the patients receiving placebo compared with those receiving no treatment.’
    • ‘A substantial number of patients who take placebos report not only side effects but improvements in symptoms as well, suggesting that much of the benefit of antidepressants is simply placebo effects.’
    • ‘And trust is a priceless asset in medicine, where a placebo can work wonders.’
    • ‘Is it unethical for a doctor to knowingly prescribe a placebo without informing the patient?’
    medication, medicament, remedy, cure, nostrum, patent medicine, quack remedy, panacea, cure-all, drug, prescription, dose, treatment
    View synonyms
    1. 1.1 A substance that has no therapeutic effect, used as a control in testing new drugs.
      • ‘After one year, patients in the placebo group had significantly more knee surgeries than those in the treatment group.’
      • ‘The eight patients treated with placebo from all dose groups were combined for the purpose of summaries and analyses.’
      • ‘The revised declaration also calls for new treatments to be tested against the current best treatment rather than placebo.’
      • ‘Compared with those on placebos, patients who received active compounds said they both felt less pain and less muscle spasticity - the spasms characteristic of this neurodegenerative disease.’
      • ‘That one doesn't get answered as often as it should, because the FDA generally only requires testing against placebo.’
      • ‘All placebo controlled trials were positive and all comparative trials indicated equivalence with other active therapies.’
      • ‘In the first phase, more patients are randomised to placebo than to active treatment.’
      • ‘Lightheadedness was reported by two patients in the placebo group, but no adverse effects were reported in the treatment group.’
      • ‘In meticulous detail it explained that some patients responded better to placebos than others, that they might respond at some times and not at others, and that considering the placebo response was essential in clinical trials.’
      • ‘The practice of testing new medicines against placebo, rather than against the best treatment available, has contributed to a general lack of knowledge.’
      • ‘The pain experienced by patients in both the placebo and cold gel groups was at the same level at the beginning of this study.’
      • ‘When checked one week after and three months after the second session, the 10 patients who had gotten placebos did slightly better than they had at the start.’
      • ‘This finding was confirmed by a study that randomised 112 patients to treatment or placebo.’
      • ‘It was used to investigate the different effects of ultramolecular potencies compared with placebo rather than pragmatic homoeopathy.’
      • ‘Indeed, the potential use of placebos for medical benefit and their continued use in clinical trials are recent subjects of considerable interest and controversy among the lay public and scientists alike.’
      • ‘One method would be to test the current dosing regimen against shorter, delayed, or less potent regimens rather than placebo.’
      • ‘They found a significant improvement of symptoms compared to patients taking a placebo.’
      • ‘In the first week, three patients in the fusidic acid cream group and eight patients in the placebo group did not comply with the treatment protocol.’
      • ‘Thirty-eight percent of patients responded to the placebo, and 52 percent to the medicines.’
      • ‘For example, during the first year, patients receiving orlistat lost more weight than patients receiving a placebo.’
    2. 1.2 A measure designed merely to calm or please someone.
      • ‘There is some debate as to whether an argon suit inflation system keeps you warm, or merely acts as a placebo i.e. making you believe that you're warmer!’
      • ‘She says, "'I'm Not Afraid of Monsters' spray acts like a placebo to eliminate children's nighttime fears."’
      • ‘The stock markets, leisure travel, and all the other industries affected are relying on the sum of all these measures, including the placebos, to recover.’
      • ‘It's interesting that the broken crosswalk buttons were not originally designed to act as placebos (presumably).’


Late 18th century: from Latin, literally ‘I shall be acceptable or pleasing’, from placere ‘to please’.