Which herbal supplement can cause an increased risk of mania when combined with MAOIs?

St. John's wort is an herbal supplement known for its use in treating mild to moderate depression. When combined with monoamine oxidase inhibitors (MAOIs), there is an increased risk of serotonin syndrome and mania. This interaction occurs because both St. John's wort and MAOIs influence serotonin levels in the brain. MAOIs work by inhibiting the enzyme monoamine oxidase, leading to increased levels of serotonin, norepinephrine, and dopamine. St. John's wort similarly increases serotonin levels, and together, they can excessively elevate these neurotransmitter levels, potentially leading to manic episodes in susceptible individuals.

The other options—ginger, ginseng, and echinacea—do not have the same documented interactions with MAOIs that St. John's wort does. Ginger is primarily known for its anti-inflammatory and gastrointestinal properties, ginseng is often used for its adaptogenic benefits, and echinacea is widely recognized for its immune-boosting effects. None of these have significant effects on serotonin levels or present an increased risk of mania when taken alongside MAOIs.