These usually fade after a week, but it may take months to regain a sense of natural well-being. Back to top Amphetamines or speed Amphetamines stimulate the heart beat and may increase blood pressure. Users say they experience feelings of increased confidence, sociability and energy. The effects usually kick in about half an hour after taking the drug and last for several hours. As the effects wear off, users may feel irritable, restless, dizzy and anxious.
Insomnia is very common, as is depression.
Increased blood pressure can cause burst blood vessels and may, in rare cases, lead to paralysis and coma. Some people suffer a bad or toxic reaction to even low doses of amphetamines. Tolerance builds up with regular use so more of the drug has to be taken to get the same effect. This can lead to dependence. Withdrawal symptoms include depression, lethargy, heart palpitations, chills and headaches.