Missed Periods in Teens: Causes, When to Worry & What to Do

Missing four consecutive periods (amenorrhea) at age 15 is not typical and warrants medical evaluation. While menstrual cycles can be irregular in the first few years after menarche (first period), prolonged absence suggests an underlying issue that should be addressed.

Common Causes of Missed Periods in Adolescents

• Hormonal Imbalance: Polycystic ovary syndrome (PCOS), thyroid disorders (hypo-/hyperthyroidism), elevated prolactin.
• Energy Deficit: Intense athletic training, restrictive eating, low body weight/body fat (female athlete triad/RED-S).
• Stress: Significant emotional/physical stress disrupts the hypothalamic-pituitary-ovarian axis.
• Medications: Certain contraceptives (especially depot medroxyprogesterone, hormonal IUDs), antipsychotics, chemotherapy.
• Pregnancy: Always rule out first, even with reported abstinence.
• Structural Issues: Imperforate hymen, vaginal septum, Müllerian anomalies (usually present with cyclic pain).
• Chronic Illness: Diabetes, celiac disease, inflammatory bowel disease.

When to See a Doctor

Schedule an appointment if:

• No period for ≥3 months (or ≥6 months if previously irregular).
• No breast development by age 13, or no period by age 15 (primary amenorrhea).
• Associated symptoms: severe acne, excess facial/body hair (hirsutism), weight changes, fatigue, hair loss, hot flashes, pelvic pain, headaches, vision changes.
• History of eating disorder or excessive exercise.

What to Expect at the Visit

1. History: Menstrual pattern, diet, exercise, stress, medications, sexual activity, family history.
2. Physical exam: Height, weight, BMI, blood pressure, thyroid, skin (acne, hirsutism, acanthosis nigricans), pelvic exam if indicated.
3. Labs: Pregnancy test (hCG), TSH, prolactin, FSH, LH, estradiol, testosterone, DHEA-S, CBC, metabolic panel. Possibly pelvic ultrasound.

Why Early Evaluation Matters

• Identifies treatable conditions (thyroid, PCOS).
• Protects bone density (estrogen deficiency → osteoporosis risk).
• Addresses disordered eating/overtraining before long-term harm.
• Provides reproductive health education and contraception if needed.

Bottom line: Don't wait. A healthcare provider can determine the cause and create a plan to restore healthy cycles and overall well-being.