Dizziness and blackouts are symptoms of many medical conditions. They occur when not enough blood reaches the brain or when there are electrical disturbances in the brain. Most causes can be treated successfully, but some are more serious.

Dizziness is a feeling of faintness, feeling light-headed, and spinning or rocking movements when you're still. Blackouts, also called syncope, are a loss of alertness or awareness lasting only a few minutes.

Standing in one place for too long, straining during bowel movements, fatigue, hyperventilating, standing up suddenly, and dehydration from the flu or other illnesses can lead to dizziness and blackouts. A drop in blood pressure or blood sugar levels are common causes, and coughing, ear infections, fever, colds and allergies can cause dizzy spells and loss of awareness.

Dizziness and blackouts can occur when you feel shock, fear, grief, loss, pain, rage, or other emotional distress.

Central nervous system diseases, irregular heartbeat, stroke, multiple sclerosis, seizures, brain tumours, and a heart attack can cause dizziness and blackouts. There are usually other symptoms with serious illnesses, including chest pain, headaches, vision changes and speech difficulties.

Drugs used for nasal congestion, allergies, high blood pressure and anxiety can cause dizziness or blackouts. Alcohol use and illegal drug use are other causes.