Hypothyroidism and ulcerative colitis: what to know

Hypothyroidism affects thyroid hormone production and may cause fatigue, cold intolerance, constipation, hoarse voice or generalised weakness. Ulcerative colitis is inflammation of the lining of the large bowel. It may cause diarrhoea, urgency, blood or mucus in stool, abdominal pain and periods of flare and remission. These conditions can overlap in how unwell you feel, but constipation is not the typical bowel pattern of active ulcerative colitis. One diagnosis does not confirm the other.

Arrange a GP consultation when bowel symptoms change, thyroid symptoms persist or a treatment is being started. Bring a complete medicine list, including thyroid and colitis treatments, and describe stool frequency, bleeding, pain, urgency and weight change. Clinicians may use examination and blood or stool tests to assess inflammation, anaemia and thyroid function, with specialist testing when indicated. Do not stop colitis or thyroid treatment without medical advice.

Seek urgent help for heavy rectal bleeding, severe abdominal pain, repeated vomiting, a swollen abdomen, fainting, confusion, high fever or signs of dehydration such as very little urine. Contact your care team promptly for worsening diarrhoea, new blood in stool or inability to keep medicines and fluids down. Colorectal cancer screening decisions depend on personal risk and clinical history, not on a single symptom.

Ask which symptoms suggest thyroid dysfunction and which suggest colitis activity, whether your medicines interact, and when blood or stool tests are needed. Discuss a written flare plan, follow-up timing and whether colorectal cancer screening is appropriate for your history.