I have been having hard-to-pass pebble-like stool for my whole life. i eat right and drink lots of water. can stool softeners be taken long term?

Yes and no: Your stool reflects your diet. Make a diet diary of what you eat for a week. Foods that cause constipation are the grains such as rice, oats, barley. Also foods that have lots of pectin (bananas) and milk. Stop these for a week and your stool will soon change.

Diet & schedule: The primary roles of the large intestines is water extraction & storage. If you don't empty often enough your stool will always be dryer & pebbly. Foods like apples, bananas & breads tend to produce slow emptying. Some stool wetting agents like Miralax can be taken long term without problems. If you schedule more emptying & avoid slowing agents this may self correct over time.

IBS: Need high fiber in diet , about 25-35 gyms /day Using stool Softners will help, but you need to increase. fiber in your diet , increased water, increased mobility such as. Walking every day. You may add fiber supplement (such as Benefiber, citrucel,, fiber choice) fresh leafy fruits and vegetables must be added .