Any of various forms of stimulation thought to arouse sexual excitement. They may be psychophysiological (arousing the senses of sight, touch, smell, or hearing) or internal (e.g., foods, alcoholic drinks, drugs, love potions, medicinal preparations). Most foods traditionally believed to be aphrodisiacs have no chemical components that would have such an effect. In some cases, their reputation may be based on a supposed resemblance to genitalia (e.g., ginseng root, rhinoceros horn). Drugs such as alcohol or marijuana may lead to sexual excitation by lessening the user's inhibitions. Few medical studies have been conducted; the only substances medically recognized as aphrodisiacs are extremely hazardous to the health.