Side effects that come with bromhexine therapy are mild and affect very few people. Some of the conditions that may be experienced are [nausea], [diarrhea], [indigestion] and [bloating]. As it also crosses the blood brain barrier, it may cause [vertigo] and [headache]. It is very rare but some people may develop serious [allergy|allergic] reactions from using bromhexine. Symptoms that indicate hypersensitivity are appearance of skin rashes, breathing difficulties and swelling of face, lips, throat or tongue. When these occur, seek medical intervention as soon as possible.