You are constipated if you pass stools less often than usual for you, they are hard or lumpy, or they are difficult to pass. Common causes include a low-fibre diet, not drinking enough, being inactive, a change in routine, stress, pregnancy, and certain medicines such as some painkillers and iron supplements.
To relieve it naturally: gradually increase fibre from fruit, vegetables, wholegrains and pulses; drink more fluids; move more; and go to the toilet when you feel the urge rather than holding on. A footstool to raise the knees can make passing stool easier. These changes can take a few days to weeks to work.
A pharmacist can suggest a suitable laxative for short-term use if needed. See a doctor if constipation lasts despite these measures, is a new and unexplained change in your bowel habit (especially over 50), or comes with blood in the stool, unexplained weight loss, persistent abdominal pain, or vomiting.