A sensible doctor, and there are many, does not prescribe dangerous drugs unless normal procedures fail (and the patient referred to specialists).

Leg cramps are common, not all treatments work of a specific individual. RLS (restless leg syndrome) often accompanies. Simple actions, such as more fluids, flexing muscles by walking or riding a bike, etc.- but they might be symptoms of something more serious. Sometimes Tylenol helps, but too large use of this over-the-counter drug can lead to severe liver problems. Good medical advice and follow-through are essential if cramps are seere or cause change in your activities or lack of sleep.

In our area of lack of effective sunlight (Canada), most general practicioners recommend that all patients take vitamin D supplement at the rate of about 1000 units per day.
Diets are often low in potassium, and supplements (bananas, sea salt, pickling brines utilizing potassium, etc.) are simple.

Methotrexate (for rheumatoid arthritis) has side effects, including nausea, loss of appetite (and in extreme cases loss of hair), bodily discomfort including leg pain, are warning signs that should cause the doctor to rethink his prescription of this drug. It has its uses, but side effects should be watched for. A good article is put out by the U. S. NIH- http://www.nlm.nih.gov/medlineplus/druginfo/meds/a682019.html

Also see Mayo Clinic summary, http://www.mayoclinic.com/health/rheumatoid-arthritis/DS00020/tab=InDepth
The Mayo Clinic has published a good book on arthritis and treatments (many depend on your life style, not drugs).

(Cortisone shots have helped my hips, but could be useless for someone else, do not take my experience as applicable to you).

Lots of good data on the net about drugs and their side effects, from National Institute of Health, Mayo Clinic, etc.
But your doctor should have carefully instructed his patients about side effects of drugs that he prescribes.