Why Your Thyroid Medication Might Make You Tired

Why do some people feel worse after starting thyroid medication instead of better?

In this episode, Chloe and Alex explore a My Adrenal Life topic that many patients recognize but rarely see explained clearly: the two-way relationship between cortisol and thyroid hormones.

Most people are taught to think of thyroid and adrenal problems as separate issues. But biologically, these systems are closely connected. Thyroid hormone helps drive metabolism, while cortisol helps support blood pressure, blood sugar stability, and the body’s ability to tolerate that metabolic demand.

This episode explains why thyroid medication can sometimes make a person feel more shaky, anxious, nauseous, or exhausted when underlying adrenal insufficiency has not been recognized first.

Chloe and Alex break down the difference between the:

• HPA axis (hypothalamus-pituitary-adrenal)

• HPT axis (hypothalamus-pituitary-thyroid)

and explain why these systems must work together.

Using a simple analogy, the episode describes thyroid hormone as the gas pedal and cortisol as the oil and coolant. Thyroid medication can increase the body’s metabolic demand, but if cortisol is too low, the body may not be able to support that shift safely.

Topics covered in this episode include:

• why thyroid medication can worsen symptoms in someone with low cortisol

• how thyroid hormone can increase cortisol clearance

• why this can create a dangerous mismatch in patients with adrenal insufficiency

• how cortisol affects conversion of T4 into active T3

• how low cortisol may contribute to higher reverse T3

• the difference between primary and central thyroid and adrenal disorders

• why a “normal” TSH does not always rule out a serious endocrine problem

• how Secondary and Tertiary adrenal insufficiency can be missed

• why treating thyroid issues without evaluating cortisol first can sometimes trigger adrenal crisis

The episode also explores the history of Schmidt’s syndrome and Autoimmune Polyglandular Syndrome Type 2, conditions that remind us autoimmune endocrine disorders often do not happen in isolation.

Beyond the lab work, Chloe and Alex also talk about the lived experience of this mismatch. Many people describe feeling “wired but tired,” with racing heart, shakiness, brain fog, low blood sugar symptoms, and a sense that their body cannot tolerate even normal stress. The episode explains why those reactions are not imagined and may reflect a real hormone imbalance rather than simple anxiety.

This conversation is especially relevant for people with:

• Primary adrenal insufficiency (Addison’s disease)

• Secondary adrenal insufficiency

• Tertiary adrenal insufficiency

• steroid-induced / iatrogenic adrenal suppression

• central hypothyroidism

• unexplained worsening after starting thyroid replacement

At its core, this episode is about understanding that the endocrine system works as a network, not as isolated glands. When one part is under strain, treating another part without looking at the full picture can make symptoms worse.

If thyroid medication has ever made you feel more unstable instead of more energized, this episode offers important context for that experience.

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