Tiredness following chemotherapy is common.
Chemotherapy can cause tiredness due to many reasons. It may be due to direct effect of the drugs (I expect
that your husband was given a combination of 5FU, Leukovorin, and either Oxaliplatin or Irinotecan), or
nutritional deficiency caused by chemotherapy-induced anorexia (chemotherapy causes nausea or vomiting), and
surgical or radiation adverse effects.
Steroids are given along with chemotherapy to prevent vomiting. Sudden withdrawal of steroids also leads to
fatigue.
Ask your husband to take regular meals, and to watch for any fever or diarrhea. If these symptoms develop, he
should report immediately to his doctor.
If the tiredness persists, you may like to take an appointment with your oncologist.