What you should do for low cortisol depends entirely on how low it actually is. Clinically low cortisol, known as adrenal insufficiency, is a serious medical condition that requires daily hormone replacement. Mildly low or borderline levels often respond to changes in sleep, nutrition, and stress management. The first step is getting a proper diagnosis, because the symptoms of low cortisol overlap with dozens of other conditions, and treating the wrong problem wastes time.
How Low Cortisol Gets Diagnosed
Cortisol follows a sharp daily rhythm, peaking in the early morning and dropping to its lowest point around midnight. That’s why doctors test it with a blood draw between 7 and 9 a.m., when levels should be at their highest. A morning cortisol reading below about 3.5 mcg/dL (96 nmol/L) strongly suggests adrenal insufficiency, with roughly 95% specificity in studies. Levels above 12 mcg/dL (332 nmol/L) generally indicate your adrenal glands are working fine.
The gray zone between those two numbers is where things get murkier. If your morning cortisol falls in that range and you have symptoms, your doctor will likely order a stimulation test. This involves an injection of a synthetic hormone that tells your adrenal glands to produce cortisol, followed by blood draws to see how they respond. Endocrine Society guidelines also support using a morning cortisol below about 5 mcg/dL (140 nmol/L) paired with another hormone measurement as an initial screening tool.
Saliva tests sold online for “adrenal fatigue” are a different matter entirely. The Endocrine Society states plainly that no scientific proof exists to support adrenal fatigue as a medical condition, and the tests marketed for it are not based on validated science. If you’re experiencing persistent fatigue, weakness, or dizziness, getting a standard morning blood cortisol through your doctor is the reliable starting point.
Hormone Replacement for Adrenal Insufficiency
If testing confirms adrenal insufficiency, the cornerstone treatment is replacing what your body can’t make. The standard recommendation is 15 to 25 mg of hydrocortisone daily, split into two or three doses. Most people take the largest dose in the morning to mimic the body’s natural cortisol peak, with a smaller dose in the early afternoon. Some people do better on an alternative steroid at 3 to 5 mg per day, which lasts longer and requires fewer doses.
Finding the right dose is surprisingly individual. Research shows that the body’s natural cortisol production varies more than fivefold between people, yet the recommended replacement range only spans about 1.7-fold. This means some people feel undermedicated at 15 mg while others feel overly wired at 20 mg. Expect some fine-tuning with your doctor over weeks or months, adjusting based on how you feel, your energy levels, and follow-up lab work.
People on long-term steroid replacement also need to pay attention to bone health. Corticosteroids can thin bones over time, so getting adequate calcium and vitamin D through diet or supplements is part of the ongoing plan.
Sick Day Rules and Adrenal Crisis
Anyone with diagnosed adrenal insufficiency needs to understand “sick day” dosing. Your body normally ramps up cortisol production during illness, injury, or surgery. When your adrenals can’t do that, you have to increase your medication manually, or you risk an adrenal crisis.
An adrenal crisis starts with deceptively ordinary symptoms: fatigue, nausea, vomiting, abdominal pain, dizziness. Without treatment, it progresses rapidly to dangerously low blood pressure, confusion, and loss of consciousness. The emergency treatment is 100 mg of hydrocortisone given by injection, followed by 200 mg over the next 24 hours. Most people with adrenal insufficiency carry an emergency injection kit and wear medical alert identification so that first responders know what to do.
Diet and Sodium for Low Cortisol
Cortisol works closely with aldosterone, the hormone that controls sodium balance. In primary adrenal insufficiency (Addison’s disease), both hormones are often low, which means your kidneys dump sodium instead of retaining it. This leads to salt cravings, low blood pressure, and dehydration. A higher sodium diet can help, though the exact amount should be guided by your doctor or a dietitian based on your specific lab results and blood pressure readings.
Beyond sodium, there’s no single “adrenal diet,” but the basics matter more than usual when your cortisol is low. Eating at regular intervals helps prevent blood sugar dips, which your body would normally correct with a cortisol surge. Protein and complex carbohydrates at each meal provide more stable energy than simple sugars. Skipping meals or intermittent fasting can be particularly rough on people with low cortisol because there’s no hormonal safety net to keep blood sugar steady.
Supplements and Adaptogens
Two supplements come up repeatedly in conversations about cortisol support: ashwagandha and licorice root. They work through completely different mechanisms, and neither is a substitute for medical treatment in true adrenal insufficiency.
Ashwagandha has the stronger clinical evidence. A meta-analysis of 15 trials covering 873 people found that ashwagandha supplementation produced a statistically significant reduction in cortisol levels and perceived stress after eight weeks. That sounds counterintuitive if your cortisol is already low, but the picture is more nuanced. In people under chronic stress, cortisol can swing between spikes and crashes rather than maintaining a healthy rhythm. Ashwagandha appears to help smooth out that pattern rather than simply pushing cortisol in one direction.
Licorice root takes a more direct approach. Its active compound blocks an enzyme in the kidneys that normally breaks cortisol down into an inactive form. A study using 225 mg of the active compound daily for seven days showed a measurable shift in how cortisol was processed, effectively allowing the body’s existing cortisol to stick around longer. The catch is that this same mechanism can cause the body to retain too much sodium, raising blood pressure. People with hypertension or heart disease should avoid it, and even healthy individuals should use it cautiously and for limited periods.
Sleep and Light Exposure
Your cortisol rhythm is tightly linked to your sleep-wake cycle, and poor sleep is one of the most common reasons for a flattened cortisol pattern. The single most impactful change for many people is consistent sleep and wake times, particularly the wake time. Getting up at the same hour every day, including weekends, helps anchor the cortisol awakening response, which is the natural surge that gets you alert in the morning.
Light exposure plays a role, though the research is more complex than popular advice suggests. A study exposing subjects to approximately 10,000 lux of bright light (equivalent to outdoor light at dawn) actually suppressed cortisol levels during the rising phase of the cortisol rhythm, reducing them for about two and a half hours. This doesn’t mean morning light is bad for cortisol. Rather, bright light helps calibrate the overall circadian system, which over time leads to a more robust and properly timed cortisol rhythm even if the acute effect on any single morning is a mild dip. The key is consistency: regular light exposure in the morning and dim light in the evening trains your body’s clock to produce cortisol at the right times.
Stress Management and Exercise
Chronic psychological stress is one of the most reliable ways to dysregulate cortisol. The pattern typically starts with elevated cortisol that, over months or years, gives way to a blunted response where your adrenals stop reacting appropriately. This isn’t adrenal “fatigue” in the way alternative practitioners describe it, but it is a real phenomenon of hypothalamic-pituitary-adrenal axis downregulation.
Moderate exercise supports healthy cortisol rhythms, but intensity matters. Walking, swimming, yoga, and light resistance training tend to normalize cortisol patterns. High-intensity training, especially when combined with poor sleep or undereating, can push cortisol lower in people who are already depleted. If you feel worse after intense workouts, with fatigue that lingers for hours or into the next day, dialing back the intensity is a reasonable move while you address the underlying issue.
Mindfulness-based practices, including meditation and breathing exercises, have consistent evidence for reducing the kind of chronic stress activation that disrupts cortisol. Even 10 to 15 minutes daily can shift the balance over several weeks. The goal isn’t to eliminate stress responses entirely but to restore the flexibility of the system so cortisol rises when it should and falls when it should.