Some or most tend to increase heart rate and core temp. Different ones have different ingredients that cause this. Caffeine really just gives you some energy. The amounts of heart rate increase I am refering to are closer to a dangerous level. Some of the more potent one will make you reach upwards of 140/90.
There are some thermogenic supplements on the market that will do this at a much safer dose. I have used BSN Atrophex and Xyience XLR8, which are mure of a natural solution. Atrophex helps to curb appetite, slightly increases core temp, and makes you urinate alot (this is because it rids your body of excess water that is retained.) When on it I was drinking about 2 gallons of distilled water a day. Really it just helped me keep water weight off and added a little extra bit of calorie burning to my day. If I carried 2 one gallon paint cans 20ft I would have broken out in a sweat like I had been running a 1/2 mile.
Here is an example of a more extreme substance that is available. Please read thoroughly.
The real deal: There is real stuff available out there that is a little more dangerous and is a little more lucrative. This is where you should check out the sites referenced above. Body builders use things alot before competitions to shred fat away. One of the more popular one I have been researching lately is Clenbuterol and it's stack. Clen is a bronchodialator (asthma medication) that has not been approved by the FDA because Albuterol is cheaper for companies to use and it has no anabolic effects. Clen will increase your resting heart rate and core temp a good amount, especially compared to the stuff at GNC... Clen is stacked with Ketotifen (antihystemin)and T3 Cytomel (hormonal metabolic stimulator) When stacked in a very very very strict and timed cycle during a 6 week time period it has shown to have positive results. It has also been said to have anabolic effects like lean muscle gains. Control tests have shown that subjects that use this along with exercise and diet have lost a good amount of body fat and gained a small percentage of lean muscle. However if not taken properly (as in proper dosage and times) it has been known to cause heart attacks, even in younger adults 17-35. I would read alot about whatever you decide and when you are done I would read some more. You have to watch out for fake or wrong stuff when ordering. these types of things and the market is very lucrative as this is not used in the U.S. except for lab purposes.
*Disclaimer: I am not a chemist or a scientist. I am passing along what I have learned and the knowledge of these supplements. I have not personally tried Clenbuterol or the Clen stack. I do not condone the use of any supplements or drugs for use other than how it was originally intended. I do acknowledge that everyone is different and everyone's body reacts differently to different substances.
These are some of the sources that I have found and there are many more but these proved to be most useful. There is also a case study on it that I cannot find right now... There are many similar products on the market and research should be done on all of them prior to taking.
I like this one for the stacking info not for ordering: