Thermo Burn Pro's label contains no caffeine — but it does contain Bitter Orange Fruit Extract, and that ingredient deserves its own explanation.
Bitter Orange (Citrus aurantium) is a source of synephrine, a compound structurally related to (but distinct from) ephedrine and adrenaline. It's used in weight-management formulas for its thermogenic and appetite-related effects.
Synephrine can raise heart rate and blood pressure in some people, particularly at higher doses or in combination with other stimulant-adjacent ingredients — and this formula also contains Cayenne and Korean Ginseng, both of which carry mild stimulant-like potential of their own.
"No caffeine" is true and worth knowing, but it isn't the same as "no stimulant effect whatsoever." If you have high blood pressure, a heart condition, or are generally sensitive to stimulants, that combination is worth discussing with a doctor before starting.