Effect of colour of drugs: systematic review of perceived effect of drugs and of their effectiveness.
OBJECTIVE
To assess the impact of the colour of a drug's formulation on its perceived effect and its effectiveness and to examine whether antidepressant drugs available in the Netherlands are different in colour from hypnotic, sedative, and anxiolytic drugs.


METHODS
Systematic review of 12 published studies. Six studies examined the perceived action of different coloured drugs and six the influence of the colour of a drug on its effectiveness. The colours of samples of 49 drugs affecting the central nervous system were assessed using a colour atlas.


METHODS
Perceived stimulant action versus perceived depressant action of colour of drugs; the trials that assessed the effect of drugs in different colours were done in patients with different diseases and had different outcome measures.


RESULTS
The studies on perceived action of coloured drugs showed that red, yellow, and orange are associated with a stimulant effect, while blue and green are related to a tranquillising effect. The trials that assessed the impact of the colour of drugs on their effectiveness showed inconsistent differences between colours. The quality of the methods of these trials was variable. Hypnotic, sedative, and anxiolytic drugs were more likely than antidepressants to be green, blue, or purple.


CONCLUSIONS
Colours affect the perceived action of a drug and seem to influence the effectiveness of a drug. Moreover, a relation exists between the colouring of drugs that affect the central nervous system and the indications for which they are used. Research contributing to a better understanding of the effect of the colour of drugs is warranted.
de Craen
A J
AJ
Department of Clinical Epidemiology, Academic Medical Centre, University of Amsterdam, Netherlands.
Roos
P J
PJ
de Vries
A L
AL
Kleijnen
J
J
D014151:Anti-Anxiety Agents / Q000627:therapeutic use; D000928:Antidepressive Agents / Q000627:therapeutic use; D002491:Central Nervous System Agents / Q000627:therapeutic use*; D002626:Chemistry, Pharmaceutical; D003116:Color; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use; D010361:Patients / Q000523:psychology; D010465:Perception; D010919:Placebos; D016032:Randomized Controlled Trials as Topic; D013607:Tablets; D016896:Treatment Outcome
D014151:Anti-Anxiety Agents; D000928:Antidepressive Agents; D002491:Central Nervous System Agents; D006993:Hypnotics and Sedatives; D010919:Placebos; D013607:Tablets