Capoten information. Capoten (captopril) is an angiotensin-converting enzyme (ACE) inhibitor, used medically for the treatment of high blood pressure. Although the exact underlying mechanisms behind the activity of Capoten (captopril) are not fully understood, effect appears to lower blood pressure and have a beneficial effect on blood circulation in patients with congestive heart failure mainly by suppressing the renin-angiotensin-aldosterone system. Capoten dosage and side effects. The suggested dosage of Captopril schedule includes starting with only 25 mg, or 1/2 tablet per day. Due to its tendency to cause fatigue, the dosage of Captopril is usually taken at night before bed so as to not interfere with the quality of ones day or training. This dosage of Captopril canbe increased over time, but no more than 50 or 100 mg is ever suggested per day. And due to the previously mentioned Captopril risk of low blood pressure, one should certainly not mistake this as a recommendation to take one or two Captopril tabs per day and not worry about it. Due to the already mentioned risk of low blood pressure, one should take extreme caution when fiddling with Captopril. Symptoms of this include dizziness and weakness, which may indicate a need for immediate medical intervention, so take extreme caution. It is especially advisable to take care and follow your blood pressure. Aside from the primary worry of low blood pressure, other potential side effects of Captopril are numerous and include the mentioned dizziness, headaches, diarrhea, constipation, loss of appetite, nausea, flushes and fatigue.