All parts of marigold contain an irritating juice, and poultices of the dried leaves have served to produce skin irritations that were thought to ease rheumatic pains. A drop of the caustic juice squeezed from a leaf or the stem may irritate warts away. The plant is edible after boiling.
Do not eat the raw leaves; they can cause violent gastritis and are toxic to the heart. External application of the leaves can cause blistering.