Why does the body itch after taking traditional Chinese medicine for phlegm-dampness resolution?

Itching after taking traditional Chinese medicine (TCM) for phlegm-dampness resolution is generally attributed to one of two causes: 1) eruption of rashes (“tou zhen”) or 2) drug allergy.

1) Eruption of rashes (“tou zhen”): When dampness becomes stagnated internally and cannot be expelled through conventional methods, physicians may prescribe herbs that promote the eruption of rashes as a therapeutic strategy. In such cases, discontinue the medication immediately and consult your attending physician before proceeding further.

2) Drug allergy: The patient may have developed an allergic reaction to one or more ingredients in the herbal formula, manifesting as generalized pruritus. Immediately discontinue the medication. If the allergic reaction is mild and does not worsen after discontinuation, no further intervention may be necessary. However, if the reaction is severe—or if symptoms continue to progress despite stopping the medication—the allergen is likely not solely (or even primarily) the prescribed herbal formula. In such cases, seek immediate medical attention at a hospital to identify the allergen and receive appropriate treatment under professional guidance. Do not self-medicate.