It could be a bona fide medical condition
Your issue could also be stemming from hyperhidrosis, a condition that affects roughly 3% of the population and causes excess sweating in the hands, feet, face, and armpits. "The exact physiologic mechanism of hyperhidrosis is not fully understood," explains Dr. Christopher Carrubba, co-director of tutor development at Med School Tutors, "but many researchers believe that it is related to an overactive sympathetic nervous system. It can also be tied to many serious medical conditions including hyperthyroidism, diabetes, heart attacks, and infections like malaria or tuberculosis."
Hyperhidrosis can occur "with or without the presence of an offensive odour," so if you're in the former group you may be particularly desperate. Since an underlying condition may be to blame (otherwise known as secondary hyperhidrosis), it's important to see a doctor if you notice you're dripping way more sweat than usual. Having to change shirts after a Thai dinner could indicate diabetes, for example, though you'll probably need a battery of tests to pinpoint the problem.
Otherwise, here are some other ways to keep your cool and combat misty polo shirts.