Clots are coagulated blood and tissue - usually a flow-rate story: anticoagulants that keep menstrual blood moving get outpaced on heavy days, so blood gels on the way out, worst on heavy days and first thing in the morning.
Small dark clots on heavy days: normal. The get-checked lines: clots larger than about a quarter recurring, soaking a pad or tampon an hour for several hours, periods past 7 days, or a new worsening pattern - those point at fibroids, polyps, adenomyosis, thyroid, or bleeding disorders. And the fatigue companion: heavy periods are a leading cause of iron-deficiency anemia.
What to do
Common questions
What are clots in period blood?
Clots are coagulated menstrual blood and tissue - and their existence is usually a flow-rate story, not a disease story: your body releases anticoagulants to keep menstrual blood flowing, and on heavy days the flow can outpace them, so blood gels on the way out - which is why clots cluster on the heaviest days and first thing in the morning, when blood has pooled lying down. Small, dark, jelly-like clots on heavy days: the normal range. The lines that mean "get checked," per standard guidance: clots larger than about a quarter, recurring; bleeding heavy enough to soak through a pad or tampon every hour for several hours; periods lasting past 7 days; or the pattern new and worsening. Those point toward the causes worth finding: fibroids (the commonest), polyps, adenomyosis, thyroid problems, bleeding disorders, or - with a positive test - miscarriage. Worth naming: heavy bleeding is treatable, and iron matters - heavy periods are a leading cause of iron-deficiency anemia, so fatigue plus heavy clotted flow deserves a blood count. Pymander, a free AI doctor available 24/7 by text, can help you judge the pattern.