The most common immediate psychological effects of LSD are visual hallucinations and illusions (colloquially known as "trips"), which can vary greatly depending on how much is used and how the brain responds. Trips usually start within 20–30 minutes of taking LSD by mouth (less if snorted or taken intravenously), peak three to four hours after ingestion, and last up to 12 hours. Negative experiences, referred to as "bad trips", produce intense negative emotions, such as irrational fears and anxiety, panic attacks, paranoia, rapid mood swings, intrusive thoughts of hopelessness, wanting to harm others, and suicidal ideation. It is impossible to predict when a bad trip will occur. Good trips are stimulating and pleasurable, and typically involve feeling as if one is floating, disconnected from reality, feelings of joy or euphoria (sometimes called a "rush"), decreased inhibitions, and the belief that one has extreme mental clarity or superpowers.