Some of the common short-term effects of amphetamine include nervousness, insomnia, headaches, increased blood pressure and heart rate, and loss of appetite. Other symptoms may include increased anxiety, irritability, negative affect and worsening motor tics. Side effects due to the action of amphetamines on the digestive system may include vomiting, nausea and abdominal cramps. High doses of amphetamines can also induce symptoms of psychosis and agitation in some (but not all) healthy individuals, that are similar to schizophrenia. Such drug-induced psychosis often involves paranoid delusions, hallucinations, violent behavior and occasionally disorganized speech. High doses of amphetamines can lead to cardiotoxicities including arrhythmias and infarctions that can be fatal.
When used at doses prescribed for the treatment of ADHD, the side effects of Adderall are not severe in most patients. The use of stimulants such as amphetamines and methylphenidate were shown to be effective and well-tolerated when taken over several years. However, whether long-term use affects cognitive abilities or other biological functions requires further investigation.
Long-term use of amphetamines can lead to drug dependence and addiction. Methamphetamine is a widely used illicit drug and most of the information on the long-term effects of amphetamine use is based on methamphetamine abuse. Long-term use of methamphetamine is associated with anxiety, depression, weight loss, dental problems and psychosis. Long-term methamphetamine use can also increase the risk of cardiac complications including arrhythmias and infarction. Long-term use of amphetamines can result in the neglect of social and occupational responsibilities and can cause irreparable damage to close relationships.
Abuse of prescription amphetamines or use of illicit amphetamines are also associated with neurotoxic effects. Chronic amphetamine abuse can cause neurotoxic effects that generally involve brain regions with the highest concentration of the dopamine neurons such as the striatum. This can also result in damage to serotonin neurons in the hippocampus, striatum and the frontal cortex. Amphetamine abuse is often comorbid with other psychological disorders, making it difficult to discriminate the impact of amphetamine abuse on cognitive function and behavior. However, studies suggest side effects include the impairment of memory, executive function and psychomotor functioning.
There has been a concern, however, regarding the use of stimulants such as amphetamine or methylphenidate in children with ADHD. Some of these concerns are related to ADHD being comorbid with substance use disorders and that treatment with amphetamines may increase the risk of addiction in such individuals. However, most studies do not support the association between treatment with amphetamines and substance use disorders, at least when treatment onset is in primary school. The onset of treatment in secondary school, however, increases the chances of developing an addiction. However, this may be due to the relationship between adolescence and drug abuse.