I pulled this information off another board - I thought it was useful
What is Clenbuterol?
Clenbuterol is a beta-2 agonist and is used in many countries as a broncodilator for the treatment of asthma. Because of it's long half life, clenbuterol is not FDA approved for medical use. It is a central nervous system stimulant and acts like adrenaline. It shares many of the same side effects as other CNS stimulants like ephedrine. Contrary to popular belief, Clenbuterol has a half life of 35 hours and not 48 hours.
Dosing and Cycling
Clenbuterol comes in 20mcg tablets, although it is also available in syrup, pump and injectable form. Doses are very dependent on how well the user responds to the side effects, but somewhere in the range of 5-8 tablets per day for men and 1-4 tablets a day for women is most common. Clenbuterol loses its thermogenic effects after 6-8 weeks when body temperature drops back to normal. It's anabolic/anti-catabolic properties fade away at around the 18 day mark. Taking the long half life into consideration, the most effective way of cycling clen is 2 weeks on/ 2 weeks off for no more than 12 weeks. Ephedrine can be used in the off weeks.
Clenbuterol vs Ephedrine vs DNP
Ephedrine will raise metabolic levels by about 2-3 percent and 200mg of DNP raises metabolic levels by about 30 percent. Clenbuterol raises metabolic levels about 10 percent and it can raise body temperature several degrees.
DNP is by far the most effective fat burner but many people will never use it because of the risks associated with it. It also offers no anti-catabolic benefit. Although it does have anti-catabolic effect, ephedrine short half life prevents it from being all that effective.
As far as side effects, Clenbuterol's are certainly milder than DNP's, and some would even say milder than an ECA stack. There is no ECA-style crash on Clenbuterol and many users find it easier on the prostate and sex drive. This may in part be due to the fact that Clen is generally used for only 2 weeks at a time.
INCREASED BLOOD PRESSURE
The most significant side effects are muscle cramps, nervousness, headaches, and increased blood pressure.
Muscle cramps can be avoided by drinking 1.5-2 gallons of water and consuming bananas and oranges or supplementing with GNC potassium tablets at 200-400mg a day taken before bed on an empty stomach.
Headaches can easily be avoided with Tylenol Extra Strength taken at the first signs of a headache. You may need to take double the recommended dose.
Post-Cycle Therapy: Clen is used post cycle to aid in recovery. It allows the user to continue eating large amounts of food, without worrying about adding body fat. It also helps the user maintain more of his strength as well as his intensity in the gym. Diet: Roughly the same as on cycle.
Fat loss: The most popular use for Clen, it also increases muscle hardness, vascularity, strength and size on a caloric deficit. For the most significant fat loss, Clen can be stacked with T3. Diet: A high protein(1.5g per lb of bodyweight), moderate carb(0.5g to 1g per lb of bodyweight), low fat diet(0.25g per lb of bodyweight) seems to work best with Clen.
Alternative to Steroids: Clenbuterol has mild steroid-like properties and can be used by non AS using bodybuilder to increase LBM as well as strength and muscle hardness. Diet: A moderate carb, high protein, moderate fat diet work well.
Stimulant/Performance Enhancement: It can be used as a stimulant, but an ECA stack may be a better choice because of it's much shorter half-life. Diet: To take full advantage of the stimulatory effects of Clen, Carbs must be included in the diet. Keto diet do not work well in this case.
Precautions: Is Clen for you?
The same precautions that apply to Ephedrine must be applied to Clen, although some people find ECA stacks harsher than Clen. It should not be stacked with other CNS stimulants such as Ephedrine and Yohimbine. These combinations are unnecessary and potentially dangerous. Caffeine can be used in moderation before a workout for an extra kick, although its diuretic effects may shift electrolyte balance. Drink more water if you use Caffeine.
What else do I need to know?
Most users that report bad side effects and discontinue use are those who use high doses right at the start of the cycle. The worst side effects occur within the first 3-4 days of use.
A first time user should not exceed 40mcg the first day.
Example of a first cycle:
Day5: 80mcg(Note: Increase the dose only when the side effects are tolerable)
Day13: 80mcg (Tapering is not necessary, but it helps some users get back to normal gradually)
Day 17: ECA/ NYC stack
Example of a second cycle:
Day 17: ECA/ NYC stack
Do not take Clen Past 4pm and drink plenty of water: 1.5-2 gallons a day.
All brands are not equal when it comes to Clen, different brands will yield different results.