Diagnosing hyperhidrosis typically involves a thorough medical history, a physical examination, and sometimes additional tests to rule out other potential causes of excessive sweating. A doctor will first assess the patient's symptoms, including the frequency, duration, and locations of sweating, to determine if they meet the criteria for hyperhidrosis. They will also inquire about the patient's family history, as primary hyperhidrosis often runs in families, which may provide helpful clues. A comprehensive assessment of lifestyle factors, triggers, and the impact on daily life will also be conducted to better understand the severity and extent of the condition.

In some cases, additional tests may be performed to differentiate between primary and secondary hyperhidrosis. This could include blood tests to check for underlying conditions such as thyroid problems, diabetes, infections, or hormonal imbalances. Imaging studies, such as X-rays or CT scans, might be recommended to rule out tumors or other medical issues. A specialized test known as the "Minor's Staining Test" may be used to evaluate the severity of sweating in specific areas of the body. If the hyperhidrosis is suspected to be secondary, further investigation into potential underlying causes will be required.