Many doctors will prescribe hormone-based birth control pills in an effort to regulate your cycle. These are often effective, and while many women do fine on them, there are some long-term consequences which you should keep in mind, such as increased risk of certain cancers and of stroke (especially for women over 35 who smoke). I am not completely against these though, and I do prescribe them from time to time.
If your symptoms are mild, you may be able to control the cramping and muscle pain quite well with over the counter anti-inflammatory medications such as Advil or ibuprofen. Although these too have their side effects with continued long-term use, once in awhile I see no problem with them for most patients, aside from the fact that they don’t address the reason the pain is there in the first place.
For water retention, your doctor may give you diuretics (to make you urinate more). They work, but again, they don’t deal with the reason you’re retaining water in the first place.
For severe PMS, you may be given antidepressants, which help not just with stabilizing mood, but also have been effective for reducing some of the other symptoms as well. Common side effects for these include GI disturbance, sexual side effects such as lowered libido, insomnia, and occasionally they can actually intensify feelings of depression.