Hallucinogenic drugs are substances that alter one's perceptions, thoughts, and feelings, and often cause visual or auditory hallucinations. However, not all drugs have such effects. The antonyms for hallucinogenic drugs are substances that produce little or no change in sensory perceptions, cognitive abilities, or emotional states. Examples of antonyms for hallucinogenic drugs include analgesics, which relieve pain and inflammation; anesthetics, which induce loss of sensation or consciousness; and sedatives, which reduce anxiety, agitation, and insomnia. Other examples of non-hallucinogenic drugs are stimulants, which increase alertness, energy, and attention; and depressants, which slow down the central nervous system and create a sense of relaxation or drowsiness.