Sustac is a medication that is used to treat high blood pressure. It is important to take the medication as prescribed by your doctor. Some precautions to take when taking Sustac include: Always take Sustac with a full glass of water. If you are taking Sustac for a long period of time, it is important to see your doctor regularly to make sure that your blood pressure is controlled. If you experience any side effects from taking Sustac, please contact your doctor as soon as possible. Do not drive or operate heavy machinery while taking Sustac. If you are pregnant or breastfeeding, please consult with your doctor before taking Sustac.