Medication is also a common cause of dehydration. Medications are designed to act on specific areas of the body, but they may also cause side effects that lead to excessive sweating or even dehydration in some cases. For example, diuretics can treat high blood pressure, but they also cause a person to urinate more frequently than average and may increase the amount they sweat.
Medication can cause heat intolerance by reducing the number of liquids in a person’s body. In addition, some medicines cause the body to retain water or make it harder for the kidneys to eliminate excess fluid, leading to dehydration. This is especially common in older adults taking multiple medications and should drink plenty of fluids when needed.
Another way medications may cause intolerance is by making a person feel dizzy or weak. Medicines that lower blood pressure may cause dizziness and weakness in some people. This is most likely if they take them regularly, but even a one-time dose could do it too.
Slowing the body’s ability to cool itself down through sweating is also considered a way to induce heat tolerance from medications. This means things might not go so well if a person is outside on a hot day with no shade.