What Are The Side Effects Of Atol 25mg?

I have high blood pressure 120/200 for more than a year now. Doctor has prescribed Atol 25mg. Are there any side-effects?
Gender: Male, Age: 35, Occupation: Business man (stress-ful work with lots of travel. Medium of travel - Bike (mostly) and car)
Weight: 76kgs Height: 5ft 10". No diet restrictions or regular exercise.
I am getting angry very fast and overwhelmed at very trivial things.

Please advise