The amphetamine effect is like an adrenaline rush, only longer and with a noticeable crash.

Swallowed, an amphetamine pill will come on within 15 to 30 minutes. Snorted, the effects are much quicker (5 to 10 minutes). Injection is almost instantaneous and can be overwhelming.

sensations
The sensations start as a tickling upwards from the stomach. There is often a sense of rushing forwards. The mind feels clear and focussed, more powerful, but in a more calculated way than the arrogant me-me-me effect of cocaine.

Physically, the teeth start grinding. The jaws clench. Long term addicts can actually crush their teeth to powder through incessant gnawing. Appetite is also strongly suppressed and you go to the toilet less. Blood pressure, heart rate all rise.

Mentally, you start to feel confident and elated, along with an increased desire to communicate. As the whole Central Nervous System (CNS) becomes stimulated, increasing your alertness and endurance. Often users talk fast and continually. And a lot of shit.

Speed is colder, more physical, and in many ways more unforgiving than E.

top

comedown
Small doses of speed (one line, one pill) wear off within 3-8 hours later, leaving the you fatigued but not exhausted. Hence the strong temptation to top up and continue speeding. This staves off the comedown but increases its severity. Eventually you face a "crash" rather than a manageable come down.

It's fear of the crash which keeps some people on weekend- even week-long "speedruns".