The links below will redirect you the personal web pages of Dr. William McK. Jefferies. The copyright of the contents on these pages are owned by Dr. Jefferies and his heirs.

1. Homepage of Dr. William McK. Jefferies
2. Research Focus: “Cortisone: A Problem in Pharmaceutical Marketing
3. Safe Uses of Cortisol
4. A Continuation of the Cortisone Story: “Mild Adrenocortical Deficiency, Chronic Allergies, Autoimmune Disorders and the Chronic Fatigue Syndrome”
5. Low Dosage Glucocorticoid Therapy (Excerpts)
6. Reproduction of Dr. Jefferies Hydrocortisone Handout
7. Dr. Jefferies’ Reference Ranges for Serum Cortisol


Dr. Jefferies was an award-winning endocrinology research fellow at Harvard University in the late 1940s when the adrenal hormone cortisol (hydrocortisone) was discovered. From the start, it was obvious that hydrocortisone was amazingly effective at reversing the symptoms of such illnesses as rheumatoid arthritis. Unfortunately, the doctors soon found out that the huge doses that they used were highly toxic.

Dr. Jefferies distinguished himself by recognizing early on that the problem with cortisol was not its inherent toxicity, but the excessive doses used. He spent over a half a century trying to convince the American medical community about a few simple points:

  1. Cortisol is a natural hormone that is necessary for human life.
  2. Many illnesses are caused or aggravated by insufficient levels of cortisol in the body.
  3. These illnesses can be effectively treated and often reversed by giving the patient small amounts of cortisol.
  4. Low doses cortisol that restore the body’s normal hormone levels are extremely safe.

Dr. Jefferies has clearly been right all along. Over and over, we see the benefits of hydrocortisone and even various synthetic forms of cortisone. Unfortunately doctors still insist on using excessively high doses for while ignoring other hormones such as DHEA and thyroid hormones which act to limit the side effects of cortisol. Many recent studies have demonstrated the safety of low dose corticosteroids. Much of this research has been done using prednisone or prednisolone, but the doses that have been shown to be generally safe are comparable to or higher than the doses of hydrocortisone that Dr. Jefferies recommended. Studies showing the safety of doses of prednisone up 10 mg a day (equal to 40 mg per day of hydrocortisone) over long periods did not use DHEA to mitigate the side effects of corticosteroids or address any hypothyroidism which would make any patient more susceptible to cortisol’s potentially negative effects. It is worth noting that as excess of hydrocortisone can cause such problems as weight gain, fluid retention high blood pressure and high blood sugar, DHEA tends to reduce all of these problems. Low thyroid, on the other hand, has been found to promote fluid retention and weight gain on its own. Again, Jefferies overriding principle appeared to be that healthy metabolism depends largely on a healthy balance of key hormones.

Jefferies’ advice to physicians who are confronted with confusing test results: “When in doubt, treat the patient”