Abstract In this chapter, the importance of sweating as a bodily function is outlined, before an exploration of the conditions that result in too much or too little sweat being produced. It’s usually released in response to increasing temperatures, but there are also other triggers that can induce sweating. Certain nerves can cause sweat to be released when we get nervous or embarrassed, for example. Sweat, generated by eccrine glands, plays a role in both controlling our temperature and fighting off infection. Excessive sweating, however—known as hyperhidrosis—can be both unhelpful and distressing; an explanation of both the condition and its treatment, with creams and deodorants, tablets, injections, and even a technique called iontophoresis, are also provided in this chapter.