The Best Time to Take Dexamethasone... and Why
I am often asked, “When is the best time of day to take my dex….morning, mid-day, or bedtime”? Let’s explore the answer from the aspect of normal human physiology.
Cortisol is an adrenocorticoid produced each day by the adrenal gland. It is essential to life, is a major factor in controlling our reaction to stress, and significantly affects our moods, energy, digestion, immune system, and emotions. The adrenal gland, like many others in the body, is controlled by the pituitary “master gland” which constantly monitors body hormone levels, regulates glandular activity, and controls adrenal hormone production. Other endocrine organs such as the thyroid are also regulated by the pituitary gland. Our “master gland” produces TSH (thyroid stimulating hormone) to stimulate the thyroid gland to greater function when it senses there isn’t enough circulating thyroid hormone passing by.
In a similar manner, the pituitary monitors adrenal glands (located above the kidneys). Cortisol serum levels are diurnal, meaning they naturally fluctuate by the time of the day. Endocrinologists take two serum cortisol levels when checking adrenal gland function....one at 8:00 AM and one at 4:00 PM. Typically the morning level is much higher as the adrenal gland responds to ACTH, a regulatory hormone which stimulates the adrenal gland to produce cortisol.
Why does all this matter? It matters because dexamethasone is chemically similar to cortisol. If we take a high dose of dexamethasone at bedtime there is still a significant blood level of dex in the morning. When the pituitary discovers there is plenty of steroid in the blood passing by it decreases ACTH production. This tells the adrenal gland to not produce any cortisol on the morning following an evening Dex binge.
To further help understanding consider what happens when cortisone (dex) is taken four days in a row, the way it often used to be prescribed for myeloma. Also, consider what happens to the adrenal glands when a person suffering severe allergies is given 10 days of continuous cortisone by mouth. For ten mornings the adrenal glands are told by the pituitary to stand down....do nothing. Now assume the allergy sufferer is better and abruptly stops daily cortisone. The pituitary tells the adrenal glands to get to work, but they have become lazy, unresponsive, and do nothing. The pituitary begins screaming by producing high levels of adrenal-stimulating hormones (ACTH), but the adrenal glands respond with “yeah, whatever.....” In time they slowly do respond and again produce daily cortisol, the way they are supposed to do every morning.
In the meantime, however, the patient has no physiologic cortisol and therefore no stimulus to increase metabolic activity when the rest of the body is begging for help. A perfect example is surgery. Anesthesiologists always ask their patients if they have been taking any steroids. If they have, the doctor expects that there may be a blood pressure problem or a wake-up problem because that patient’s adrenal glands have become lazy and unresponsive. The worst of these possibilities leads to “Adrenal Crisis” which can translate to a true medical emergency.
The bottom line, therefore, is that it is much more physiologic to take all corticosteroids (Dex, prednisone, prednisolone, Solu-Medrol, etc) in the morning when the body expects there to be an elevated steroid level. You will get much less adrenal gland suppression if you take steroids in the morning than if you take them at night.
What I just described happens because of external forces......cortisone tablets given to the patient. The same thing can occur by disease, and is called Addison’s Disease, a condition in which the adrenal glands do not work properly. JFK had Addison’s Disease and it nearly killed him on several occasions. He often required steroid injections before international summits, surgery, and even day to day activities needing systemic cortisone because his adrenal glands did not work well.
Bottom line....it is much wiser to take all steroids in the morning hours, not at night. You will probably do OK if you take them at night, but your pituitary and adrenal glands will follow a normal physiologic routine if you give that steroid dose in the morning.