Mom who is 99 and has been diagnosed with an urinary tract infection and was prescribed nitrofurantoin mono mcr 100 mg was given a twice a day prescription for 5 days . When she has an uti she hears voices and her mind replays things from radio or old family conversations. Because we caught it quickly the symptoms are not as severe yet as previous episodes. On line suggests the dosage is 4x per day and the bottle is for 2x per day. She weighs about 160 and is short and heavy in the middle. Is this dosage enough. Prior uti infections responded quickly with amoxycillin but I am not confident this dosage is enough.