I"ll just add a thought on this. do not take anything beyond the recommended dosage on the bottle!! ECA's are effective but only if they are used prudently. Taking excess ephedrine can be detrimental to your health and the company has calculated what is safe for you, usually no more than 90mg/day of pure ephedrine.
As well, if you are a coffee drinker, tea drinker, cola drinker, you might want to take this into consideration b/c the added caffeine can wire you to the point that it is uncomfortable. Once again, the company has calculated how much caffeine is necessary for their product. Any excess amount you ingest should not go beyond 200 mg/day.