How do I know if a shampoo is causing my hair loss?

Several products in this category, including Mielle's Rosemary Mint line and Native's Coconut & Vanilla, have user threads alleging shedding, though causation is contested and often confounded with seasonal shedding, stress, or other routine changes. Reviewers across communities generally recommend isolating one variable at a time and giving any new shampoo at least 4–6 weeks before judging.