There are several different blood pressure medications available, such as Norvasc, Benicar, etc. If one doesn't work, there should be another that does. High blood pressure can be deadly. It can cause a stroke or heart attack. It also puts a lot of pressure on the heart, eyes and kidneys and very often seems to be accompanied by high cholesterol.
Therefore, it is to his benefit to see his doctor again to seek out something that works well for him. It is possible that he got a dosage that is too strong for him. He can accentuate the medicine by avoiding salt altogether. He should avoid grapefruit juice, limit use of coffee, regular tea, carbonated beverages, licorice, cold cuts, msg, anything that contains a lot of sodium. Helpful products are: Pomegranate juice, Jamaican June plum juice, ginger tea, 1 glass of red wine with meals, raspberry tea (decaffeinated) and aerobic activity (swimming, speed walking, treadmill workout.)
I wish I could tell you that he can control it without medication, but he would be taking a serious risk. Strokes are the major cause of disability in the US. Weight loss, and diet modification are the only home remedies, but that takes time to accomplish. In the meantime, he has to take the medicine.