Hallo Thanks for your query.
Your mother who is 81 years old is having constipation
after medication for UTI.Please note that this is not likely to be due to medication but could be age related constipation due to hard stools.Please give her a Enema
with soap water(Only Once) and once all the hard fecal matter is out put her on regular stool softener
like Naturolax granules to be taken at night.Pl ensure she takes leafy vegitables and roughage in her diet and drinks plenty of water to avoid hard stools.