Rare diseases · Sign or symptom
Loss of consciousness
Fainting
HP:0007185
What it means
Loss of awareness of oneself or one's surroundings, involving (i) a loss of normal motor control is evident as flaccidity or stiffness, either of which can be accompanied by jerking movements, and postural control is lost so that patients fall if they are in an upright position; (ii) normal responsiveness is lost; and (iii) the patient experiences amnesia for the event. Loss of consciousness my be transitory (e.g., syncope) or prolonged.
In everyday care
Most people with this sign do not have a rare disease — it appears in common conditions far more often. These general reference pages cover the same topic:
Rare diseases that can present with this30
Common30–79%
8- Acute encephalopathy with biphasic seizures and late reduced diffusion
- Carnitine palmitoyl transferase 1A deficiency
- Herpes simplex virus encephalitis
- Infantile spasms-psychomotor retardation-progressive brain atrophy-basal ganglia disease syndrome
- Jervell and Lange-Nielsen syndrome
- Marchiafava-Bignami disease
- Mercury poisoning
- Methylcobalamin deficiency type cblE
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Passing out
Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.
Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.