Amphetamine is a potent central nervous system (CNS) stimulant that is used in the treatment of attention deficit hyperactivity disorder (ADHD), narcolepsy, and obesity. Amphetamine was discovered in 1887 and exists as two enantiomers: levoamphetamine and dextroamphetamine. The mode of therapeutic action in ADHD is not known. Amphetamines are thought to block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extraneuronal space. At higher dosages, they cause release of dopamine from the mesocorticolimbic system and the nigrostriatal dopamine systems. Amphetamine may also act as a direct agonist on central 5-HT receptors and may inhibit monoamine oxidase (MAO). In the periphery, amphetamines are believed to cause the release of noradrenaline by acting on the adrenergic nerve terminals and alpha- and beta-receptors. Modulation of serotonergic pathways may contribute to the calming affect. The drug interacts with VMAT enzymes to enhance release of DA and 5-HT from vesicles. It may also directly cause the reversal of DAT and SERT. Several currently prescribed amphetamine formulations contain both enantiomers, including Adderall, Dyanavel XR, and Evekeo, the last of which is racemic amphetamine sulfate. Amphetamine is also prescribed in enantiopure and prodrug form as dextroamphetamine and lisdexamfetamine respectively. Lisdexamfetamine is structurally different from amphetamine, and is inactive until it metabolizes into dextroamphetamine.

Phenylpropanolamine belongs to the sympathomimetic amine class of drugs and is structurally related to ephedrine. The effects of phenylpropanolamine are largely the result of alpha-adrenergic agonist activity resulting from both direct stimulation of adrenergic receptors and release of neuronal norepinephrine. Phenylpropanolamine is mainly used as a nasal decongestant. Phenylpropanolamine is also used as anorexiant in obesity and to treat urinary incontinence in veteranary. Phenylpropanolamine containing products has been withdrawn by FDA due to the association of phenylpropanolamine use with increased risk of hemorrhagic stroke.

Fenethylline (generic name Captagon) is a codrug of amphetamine and theophylline. In the fenetylline molecule, theophylline is covalently linked with amphetamine via an alkyl chain. It was formerly used to treat conditions such as ADHD, narcolepsy, and depression, but its use has been banned because of the potential for abuse. Amphetamine, an agonist for trace amine-associated receptor 1 (TAAR1) with enhancing dopamine signaling (an increase of irritability, aggression, etc.), is the main cause of Captagon addiction. Theophylline, an antagonist that blocks adenosine receptors (e.g. A2aR) in the brain responsible for restlessness and painlessness, may attenuate the behavioral sensitization caused by amphetamine. Fenethylline is included in a list of compounds to be considered by a World Health Organization (WHO) Expert Committee in April 1985 for possible international scheduling under the Convention on Psychotropic Substances, 1971. Fenethylline re-emerged because of its widespread abuse by Middle Eastern young adults. Terrorist groups such as the Islamic State to enhance what they consider desirable characteristics - aggressiveness, alertness, and fearlessness - in their recruits, promote it.