Missed Periods and Stomach Issues: Common Causes and When to See a Doctor

Missed periods (amenorrhea) with gastrointestinal symptoms can stem from hormonal, gastrointestinal, or systemic conditions.

Common Causes

• Pregnancy: Most common cause of missed period; nausea, bloating, fatigue.
• Polycystic ovary syndrome (PCOS): Irregular periods, insulin resistance → abdominal weight gain, bloating.
• Thyroid disorders: Hypothyroidism (heavy/irregular periods, constipation, bloating); hyperthyroidism (light/absent periods, diarrhea).
• Stress/HPA axis dysfunction: Hypothalamic amenorrhea; alters gut motility (IBS-like symptoms).
• Eating disorders/low energy availability: Functional hypothalamic amenorrhea; GI slowing.
• IBS / IBD: Chronic GI symptoms; stress from illness can disrupt cycles.
• Celiac disease: Malabsorption → nutritional deficiency → amenorrhea + GI symptoms.
• Medications: Opioids, antipsychotics, chemotherapy, hormonal contraceptives (adjustment period).
• Perimenopause: Irregular cycles, bloating, bowel changes (age 40s–50s).

Evaluation

• Pregnancy test (urine/serum hCG).
• TSH, prolactin, FSH, LH, estradiol, testosterone.
• Pelvic ultrasound (ovaries, uterus).
• GI workup if indicated (celiac serology, stool studies, colonoscopy).

When to See a Doctor

• Missed ≥3 periods (or ≥6 months if previously irregular).
• Severe abdominal pain.
• Weight loss, blood in stool.
• Signs of thyroid disease, PCOS, eating disorder.
• Trying to conceive without success.

Primary care, OB/GYN, or gastroenterologist can initiate workup.