Pain relievers and anti-inflammatories are often tried first. Positioning and exercises under the direction of a physical therapist may be helpful. Treatment can be applied more specifically if the cause of the sciatica is known.
Anything that can put pressure on the sciatic nerve can cause sciatica. For example, a herniated disc, tumor, or infection are the most likely sources of compression. Bone spurs from arthritic changes and narrowing of the intervertebral spaces from degenerative disc disease can also contribute to sciatica.
Infection can be treated with antibiotics. Tumors may require radiation therapy to shrink the tumor first before surgery is done (if at all). Surgery to remove a herniated disc gets fast relief but the long-term results aren't any better than conservative care.
So the first step is to find out what's pinching the sciatic nerve. See a medical doctor for an examination and any imaging studies required. The doctor can lay out all treatment options for you based on your situation. The pros and cons of each approach should be considered along with expected short-term versus long-term results.