Warm water compresses, warm tea bags and application of a little castor oil are all great to reduce stye swelling. But if your stye lasts for more than a week, you should absolutely go to an ophthalmologist because you probably need antibiotics.
My mom who is a nurse once told me about a patient that came in for stye, one of his eyes was basically closed shut due to the swelling! Why would anyone wait so long to have it checked out?
It's always a good idea to show it to the doctor before you try any home treatments, especially because stye is something that often reoccurs if it happens once or twice. It's best to have professional medical insight and take any precautions.