In medicine, a prodrome is an early symptom (or set of symptoms) that might indicate the start of a disease before specific symptoms occur. It is derived from the Greek word prodromos, meaning "precursor". Prodromes may be non-specific symptoms or, in a few instances, may clearly indicate a particular disease, such as the prodromal migraine aura.
For example, fever, malaise, headache and lack of appetite frequently occur in the prodrome of many infective disorders. A prodrome can be the precursor to the onset of a chronic neurological disorder such as migraine or epilepsy, where prodrome symptoms include euphoria, scotoma, disorientation, aphasia, or photosensitivity.
It also refers to the initial in vivo round of viral replication.
Prodromal labour, mistakenly called "false labour," refers to the early signs before labour starts.
A prodrome for schizophrenia is the period of decreased cognitive functioning that is postulated to correlate with the onset of psychotic symptoms. The concept has been reconsidered as the pathways to emerging psychosis have been investigated since the mid-1990s. One example of the international paradigms aimed at researching the prodrome is the North American Prodrome Longitudinal Study (NAPLS). This study is concerned with brain development, hormones, and neuropsychological functions that may play a role in risk for and prevention of mental illness in young adulthood. The term at risk mental state is sometimes preferred, as a prodromal period cannot be confirmed unless the emergence of the condition has occurred. (Also see early psychosis.)
Prodrome, or psychosis risk syndrome as it is also known, is a proposed syndrome to be used in the DSM-5 (2013) of psychiatry. It is also defined as "the aura that precedes a psychotic break by up to two or three years." Patients with this condition "still have 'insight' - a pivotal word in psychiatric literature, indicating that a patient can still recognize an altered worldview as a sign of illness, and not a revelation." Prodrome is also sometimes called "attenuated psychotic symptoms syndrome." Chairman of the DSM-IV Task Force, Allen Frances, has criticised the concept of Psychosis Risk Syndrome on the grounds of a high rate of inaccuracy, the potential to stigmatize young people given this label, the lack of any effective treatment, and the risk of children and adolescents being given dangerous antipsychotic medication.
About one third of patients with prodrome are diagnosed with schizophrenia or other psychosis in a few years. In the North American Prodrome Longitudinal Study, researchers found that 35 percent of "patients had a psychotic break within two and a half years of enrolling at a clinic." 65 percent "found that their symptoms passed or plateaued." A psychotic break is made statistically more likely (43% vs. 35%) if the patient abuses certain drugs.[which?]
Prodromal phase of common diseases and conditions
- Diverticulitis – may worsen throughout the first day, as it starts out as small pains in the torso and/or mild diarrhea, and may slowly turn into vomiting and sharp pains in the lower left quadrant of the abdomen.
- Herpes simplex – marked by tingling (paresthesia), itching, and pain.
- Measles – marked by fever, rhinorrhea, and conjuctivitis.
- Migraine – not always present, and varies from individual to individual, but can include ocular disturbances such as shimmering lights with reduced vision, altered mood, irritability, depression or euphoria, fatigue, yawning, excessive sleepiness, craving for certain food (e.g. chocolate), stiff muscles (especially in the neck), hot ears, constipation or diarrhea, increased urination, and other visceral symptoms.
- Varicella – may or may not feature a prodrome, but at least 37% of unvaccinated children who contract chickenpox do have at least a mild febrile prodrome.
- Parkinson's Disease - Loss of smell
- Alzheimer's Disease - perhaps early impairments in behavior, personality and language 
- "Pre-cold" - "itchy, scratchy, throat [and] runny nose"
- Early warning signs of cancer
- Metzler, S; Dvorsky, D; Wyss, C; Müller, M; Gerstenberg, M; Traber-Walker, N; Walitza, S; Theodoridou, A; Rössler, W; Heekeren, K (2015). "Changes in neurocognitive functioning during transition to manifest disease: comparison of individuals at risk for schizophrenic and bipolar affective psychoses.". Psychological Medicine 2: 1–12. doi:10.1017/S0033291715000057. PMID 25640248. Lay summary.
- Yung AR, McGorry PD, McFarlane CA, Jackson HJ, Patton GC, Rakkar A (1996). "Monitoring and care of young people at incipient risk of psychosis". Schizophr Bull 22 (2): 283–303. doi:10.1093/schbul/22.2.283. PMID 8782287.
- William Carpenter, Report of the DSM-5 Psychotic Disorders Work Group, April 2009, found at DSM-5 website of the American Psychiatric Association. Accessed December 2, 2010.
- Rachel Aviv, "Which Way Madness Lies: Can psychosis be prevented?" Harper's, December 2010, 35-46, at 36. Found online at Harper's Magazine online. Accessed December 7, 2010.
- Aviv, op. cite, p. 38.
- Frances A. Psychosis risk syndrome--far too risky. Aust N Z J Psychiatry. 2011 Oct;45(10):803-4.
- Kelman L (October 2004). "The premonitory symptoms (prodrome): a tertiary care study of 893 migraineurs". Headache 44 (9): 865–72. doi:10.1111/j.1526-4610.2004.04168.x. PMID 15447695.
- Welsh-Bohmer, Kathleen= (March 8, 2008). "Defining "Prodromal" Alzheimer’s Disease, Frontotemporal Dementia, and Lewy Body Dementia: Are we there yet?".