What Supplements Lower Cortisol? What the Research Shows

Part of our Alpha GPC & NeuroMatcha guide library.

Cortisol is sometimes called the "stress hormone" (MedlinePlus), and supplements promising to lower it are easy to find. If you are juggling deadlines and poor sleep, it is fair to ask which ones have real evidence. Here is what cortisol does, what human trials found for each popular supplement, which products to avoid, and what lowers cortisol without a pill.

What you'll learn

• What cortisol does and when it is normally highest
• Which supplements lowered cortisol in human trials, and by how much
• Why lower cortisol does not always mean feeling less stressed
• Why "adrenal support" products can be risky
• Ways to lower cortisol without supplements, and when to see a provider

What is cortisol, and do you need to lower it?

Not necessarily: cortisol is a hormone your body needs every day. It is made by your adrenal glands and helps your body respond to stress, reduce inflammation, control blood sugar and metabolism, and control blood pressure (MedlinePlus). Levels are normally highest in the morning and much lower by around 4 p.m. (MedlinePlus); for how that morning rise relates to coffee, see whether you should wait 90 minutes to drink coffee.

Cortisol that is truly too high or too low is a medical problem, and without treatment it can be very serious (MedlinePlus). The only way to know your level is a blood, urine or saliva test ordered by a health care provider (MedlinePlus). Supplements are not a substitute for that testing or for treatment.

Which supplements lower cortisol?

Only a few have been tested in people, and most effects were small. Here is how the evidence lines up:

Does ashwagandha lower cortisol?

Yes, modestly, and it has the most evidence of any supplement here. A 2025 review of randomized trials found ashwagandha lowered cortisol by an average of 1.16 µg/dL compared with placebo (Albalawi, 2025). A 2026 review of 23 trials with 1,706 participants also found lower cortisol, though the studies varied a lot (Fornalik et al., 2026).

Lower cortisol did not always mean feeling less stressed. The 2025 review found no significant effect on how stressed people said they felt (Albalawi, 2025), while a 2024 review of 9 trials with 558 patients did find lower stress and anxiety scores (Arumugam et al., 2024). Ashwagandha also changed other hormones: thyroid hormone T4 rose modestly, and testosterone rose in men (Fornalik et al., 2026).

Safety matters here. Ashwagandha may be safe for up to 3 months, rare cases of liver injury have been reported, and it should be avoided during pregnancy and breastfeeding (NCCIH). It is not recommended for people with thyroid or autoimmune disorders, and it may interact with medicines for diabetes, blood pressure, seizures and thyroid conditions, as well as sedatives and immunosuppressants (NCCIH). If it makes you drowsy, see whether ashwagandha makes you sleepy.

Does omega-3 fish oil lower cortisol?

It did in one well-designed trial. In 138 sedentary, overweight, middle-aged adults, 4 months of omega-3 supplements led to lower overall cortisol during a lab speech stress test, and the group taking 2.5 grams a day had 19% lower overall cortisol than the placebo group (Madison et al., 2021).

That is one trial in one group of people, so it is promising rather than proven. Side effects of omega-3 supplements are usually mild, such as an unpleasant taste, bad breath, heartburn, nausea or diarrhea (NCCIH). For omega-3 and exercise recovery, see our recovery stack guide.

Does phosphatidylserine lower cortisol?

It may blunt the cortisol spike from acute stress, but the evidence is thin. In one trial, 3 weeks of a 400 mg soy-based phosphatidylserine complex blunted the cortisol response to a public-speaking and math stress test, but 600 and 800 mg did not (Hellhammer et al., 2004). In a second trial of 75 healthy men, 400 mg normalized the cortisol response only in men with high chronic stress, 200 mg had no effect, and it did not change how stressed the men felt (Hellhammer et al., 2014).

Both trials came from the same research group, so independent studies are still needed (Hellhammer et al., 2004) (Hellhammer et al., 2014).

Do L-theanine and matcha lower cortisol?

L-theanine may lower cortisol for a few hours after a stressful task, but not over weeks. L-theanine is an amino acid found mainly in tea (White et al., 2016); for the basics, see what L-theanine is.

• One drink: in 34 adults, a drink with 200 mg of L-theanine lowered the cortisol response to a stressful task 3 hours after drinking it, but not after 1 hour. The drink also contained small amounts of alpha-GPC, phosphatidylserine and chamomile, which the authors said may have contributed (White et al., 2016).
• One capsule: in 16 moderately stressed adults, a single 200 mg dose led to a bigger drop in saliva cortisol 1 hour later than placebo (Evans et al., 2021).
• Four weeks: in 30 adults with moderate stress, 400 mg a day for 28 days did not change saliva cortisol compared with placebo (Moulin et al., 2024).

Matcha, a powdered green tea that contains both L-theanine and caffeine, has one relevant trial: in healthy men doing 12 weeks of strength training, a matcha drink twice a day was linked to lower saliva cortisol than a placebo drink (Shigeta et al., 2023). Read more in what the research shows on matcha and why matcha feels different from coffee.

Does vitamin C lower cortisol?

It helped cortisol come back down faster in one trial, but it did not prevent the spike. In 120 healthy young adults, 2 weeks of high-dose, slow-release vitamin C (1,000 mg three times a day) led to faster cortisol recovery after a stress test, not a smaller overall cortisol response, along with a smaller rise in blood pressure and less self-reported stress (Brody et al., 2002).

That is a high dose, so talk with your provider before taking it.

Do rhodiola and magnesium lower cortisol?

The evidence for both is weak. For rhodiola, a trial in 60 adults with stress-related fatigue found a change in the cortisol response to waking after 4 weeks (Olsson et al., 2009), but a 4-week trial in 26 healthy young men found no change in cortisol (Jówko et al., 2018). NCCIH says there is not enough reliable evidence to know whether rhodiola is useful for any health purpose (NCCIH). Rhodiola is possibly safe for up to 12 weeks, may cause dizziness, headache or insomnia, and has been reported to interact with the blood pressure drug losartan (NCCIH).

For magnesium, a review describes a "vicious circle": stress may increase magnesium loss, and low magnesium may make the body more sensitive to stress (Pickering et al., 2020). Several of the review authors worked for a company that sells magnesium supplements (Pickering et al., 2020), and we did not find a good trial showing that magnesium alone lowers cortisol. For magnesium forms and combining it with turmeric, see our magnesium and turmeric guide.

Are "cortisol blockers" and "adrenal support" supplements safe?

Be very cautious with them. When Mayo Clinic researchers tested 12 "adrenal support" supplements sold in the U.S., every one contained a small amount of thyroid hormone, 25% contained the steroid drug budesonide, and 8% contained cortisol itself (Akturk et al., 2018).

Dietary supplements are not approved by the FDA before they are sold (NCCIH). A product that promises to "balance" or "block" cortisol is making a promise that the research above does not support.

How can you lower cortisol without supplements?

Relaxation practices have evidence too, and they have few risks. Slow, deep breathing may modestly lower blood pressure and cortisol, and a review of 8 studies found that focused-attention meditation reduced blood pressure and cortisol (NCCIH). Reviews have also found yoga reduced perceived stress in healthy adults (NCCIH).

Sleep and daily routine matter as well; see how to fix your sleep schedule and why you get tired after lunch. Contact your health care provider if you feel overwhelmed by stress or it is affecting your health (MedlinePlus). If you are thinking about suicide, call or text 988 (MedlinePlus).

Who should be careful with cortisol supplements?

Check with a provider first if any of these apply to you:

• Pregnancy or breastfeeding: ashwagandha should be avoided (NCCIH), and little is known about rhodiola (NCCIH).
• Thyroid or autoimmune conditions: ashwagandha is not recommended (NCCIH), and ashwagandha raised T4 in trials (Fornalik et al., 2026).
• Prescription medicines: ashwagandha and rhodiola can interact with common medicines (NCCIH) (NCCIH).
• Signs of a cortisol disorder: new fat around the base of the neck or between the shoulder blades, or wide purple streaks on the stomach, hips or under the arms, can be signs of too much cortisol and need a provider, not a supplement (MedlinePlus).

Common myths (quick reality check)

• Myth: A lower cortisol number means you feel less stressed. Reality: In one review, ashwagandha lowered cortisol without changing how stressed people felt (Albalawi, 2025).

• Myth: More is better. Reality: In one trial, 400 mg of phosphatidylserine blunted the cortisol spike, but 600 and 800 mg did not (Hellhammer et al., 2004).

• Myth: "Natural" adrenal products are gentle. Reality: Tested adrenal support supplements contained thyroid hormone, and some contained steroids (Akturk et al., 2018).

Frequently asked questions (FAQ)

What is the best supplement to lower cortisol?

Ashwagandha has the most research, with pooled trials showing a small drop in cortisol compared with placebo. It is not right for everyone, so check with a provider first.

What supplements lower cortisol fast?

In small trials, a single dose of L-theanine lowered saliva cortisol 1 to 3 hours later during a stressful task. The effect did not show up after 4 weeks of daily use.

What vitamin lowers cortisol?

Vitamin C is the only vitamin with a direct trial here. High-dose vitamin C helped cortisol come back down faster after a stress test, but it did not prevent the rise.

Does magnesium lower cortisol?

There is no strong evidence that it does. A review links low magnesium and stress, but we did not find a good trial showing magnesium alone lowers cortisol.

Does matcha lower cortisol?

Possibly a little. In one trial, men doing strength training who drank matcha twice a day had lower saliva cortisol than men drinking a placebo.

Will lowering cortisol help you lose belly fat?

The supplement trials in this article did not test weight loss. New fat around the neck or upper back can be a sign of a cortisol disorder, so see a provider.

Can you take cortisol supplements while pregnant?

Talk to your provider first. Ashwagandha should be avoided during pregnancy and breastfeeding, and little is known about rhodiola.

Related guides

• What are adaptogens?
• Does ashwagandha make you sleepy?
• What is L-theanine?
• L-theanine side effects
• Matcha benefits: what the research shows
• Should you wait 90 minutes to drink coffee?
• Mental fatigue
• How to fix your sleep schedule

Disclaimer and when to seek help

This article is for general education and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Our products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your health care provider before taking any supplement, especially if you are pregnant or breastfeeding, take prescription medicines, or have a thyroid, autoimmune or liver condition. If you think your cortisol may be too high or too low, ask your provider about testing.

References

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