This list is for reference only and is far from a complete and thorough list, you should alway conduct your own research from multiple sources in order to develop an informed opinion of wether Clen HCl is for you.

Consulting with a doctor should be advised for all people with high blood pressure and/or previously diagnosed cardio-vascular problems. New users should start building up the dose over time, users will usually see when they've reached a dose that becomes too harsh and the side effects (sides) become too bad.

Common Side Effects:
Headaches
Muscular tremors (especially hand shakes and finger jitters)
Muscular cramps
Nervousness
Insomnia
Sweating
Changes to appetite
Nausea
Palpitations
Hypertension (high blood pressure)
Possible cardiac hypertrophy as clen also targets cardiac and smooth muscle fibres.

In view of the above side effects, it is obvious to assume that anyone with cardiac issues and/or hypertension should not use a stimulant such as Clenbuterol and caution must be observed by those already using similar compounds in the treatment of existing medical conditions. In addition, there is very little conclusive knowledge of the cardiac effects of supra-physiological dosages in humans.

Some users suggest that splitting the dose may lessen side effects slightly, as there is limited accumiltion, this is a trial and error process in essence, to ascertain which method suits you personally, some users also suggest taking their dose just before bed in order to sleep thru an avoid most the side effects.

There are other suppliments you can take to help reduce the side effects and make them more pleasent, some of these follow below.

Muscular cramping
This is most probably due to depletion of the amino acid L-taurine in the liver together with deficits in the electrolytes sodium and potassium, as well as inadequate hydration. Taurine helps stabilize cell membranes and prevent nerves from becoming over-excited. Some studies show that giving taurine supplements relieves painful muscle cramps.

Symptoms of cramping may be alleviated by:
Eating fruit particularly bananas and other high potassium fruits.
Eating vegetables especially carrots and other high potassium veg.
Ensuring adequate hydration (8 glases of water is standard 12+ better on clen)
Taurine supplementation - 3-5g daily (many uses use Red Bull or Emerge before work outs)
Potassium supplementation - 200-400mg daily taken before bed on an empty stomach.

Ketotifen and Diphenhydramine
Ketotifen / Diphenhydramine are anti-histamines used medically to treat bronchial asthma and allergies. However, bodybuilders are interested in the drug as it has been shown to inhibit the down regulation of the beta receptors, including the beta 2s that clen stimulates. As long as you are taking Ketotifen / Diphenhydramine, it will continue to clean these receptors, never allowing them to downregulate, even while on a heavy clen cycle. That means you can continue to take clen indefinitely without having to cycle off to regenerate the receptors. A dose of 2-3mg daily can upregulate even severely shut down receptors within a week.

No studies have been done to find the most effective dose though most users should find 3-4mg Ketotifen or 50mg Diphenhydramine daily are ideal, which can be split or taken in one sitting. Higher doses are likely to cause (sometimes severe) drowsiness and increase appetite.

Its best to take these before bed, and find which one best suits you, as many find Diphenhydramine perfect while other prefer Ketotifen, so again trial and error.

In summary: The use of Clenbuterol will elicit higher body temperature, higher blood pressure, increased heartrate and in some cases insomnia, jitters and cramping.

More information can be found on the Excellent Muscle Talk Website, where we have used as a reference, it would also be worth checking out the forum over there, but don't be a prat.