text: One of the typical uses of additive effect is to detect synergy. Additive effect can be considered as the baseline effect in methods of determining the presence of synergistic effect between two or more drugs. Synergistic effect is similar to additive effect. The only difference is it has a combination effect greater than additive effect. To be brief, synergy can produce an effect of 2 + 2 > 4 when drugs are used in combination. The combination of angiotensin II receptor antagonist (ARB), Candesartan-cilexetil , and angiotensin-converting enzyme inhibitor (ACEI), Ramipril, demonstrates a synergistic effect in reducing systolic blood pressure.