SUPPLEMENT GUIDE

Best Supplements for Cortisol and Stress: 7 Evidence-Based Picks on Amazon

By WellnessVigor · Updated October 12, 2026 · 10 min read

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When stress drags on for weeks or months, cortisol can stay high and leave you wired at night, tired in the morning and battling cravings. Lifestyle changes come first, but some supplements have research suggesting they can help the body handle stress and may lower cortisol.

Below are 7 supplements with the best available evidence, and a popular product on Amazon for each. We have not personally tested these products; our picks are based on the ingredients and doses used in research and on third-party testing information where available. Talk to your doctor or pharmacist before starting any supplement, especially if you are pregnant, breastfeeding, take medicines or have a medical condition.

Quick answer

Ashwagandha (especially standardized root extracts like KSM-66) has the most research for lowering cortisol and stress. Holy basil, rhodiola, phosphatidylserine, omega-3 fish oil, L-theanine and magnesium have smaller or more mixed evidence. Choose one at a time, use studied doses, look for third-party testing, and combine with good sleep, regular movement and stress management.

Table of Contents

Start with the basics

No supplement can outwork poor sleep, constant caffeine and no rest. The most reliable ways to bring cortisol down are a regular sleep schedule, morning daylight, balanced meals, a daily walk and slow breathing. Read our full guide on how to lower cortisol naturally for better sleep and the signs of chronic stress and high cortisol.

How to choose a cortisol supplement

Match the studied form and dose. Research often uses specific standardized extracts, such as KSM-66 ashwagandha or Holixer holy basil.
Look for third-party testing such as USP, NSF or Informed Choice, which check that the product contains what the label says.
Avoid proprietary blends that hide doses.
Start one supplement at a time so you can tell what helps and spot side effects.
Give it time: most studies lasted 4 to 8 weeks.

Supplements work best on top of good sleep. The 14-Day Sleep Reset gives you a simple, night-by-night plan to calm your evenings and sleep deeper.

Get the 14-Day Sleep Reset Guide →

The 7 best supplements for cortisol

Use the buttons to check current prices, doses and reviews on Amazon. Always read the label and confirm certifications on the product you receive.

BEST OVERALL: ASHWAGANDHA

Transparent Labs KSM-66 Ashwagandha

Ashwagandha has the strongest research of any supplement for lowering cortisol. In a 60-day trial, 300 mg of a full-spectrum root extract twice daily significantly lowered serum cortisol compared with placebo. This product uses KSM-66, a standardized root extract used in many studies, and has been listed as tested by Informed Choice.

Pros

Most researched herb for cortisol
Standardized KSM-66 extract
Third-party tested (Informed Choice listing)

Cons

Premium price
Not suitable in pregnancy or with thyroid or autoimmune conditions

BEST BUDGET ASHWAGANDHA

Nutricost KSM-66 Ashwagandha

A lower-cost way to try a KSM-66 root extract at doses similar to those used in studies (about 300 to 600 mg a day).

Pros

Affordable
Uses KSM-66 extract
Simple single ingredient

Cons

Check for current third-party testing
Same safety cautions as all ashwagandha

BEST HOLY BASIL (TULSI)

Gaia Herbs Holy Basil Leaf

In an 8-week trial of 100 stressed adults, 250 mg a day of a standardized holy basil extract reduced perceived stress more than placebo, lowered hair cortisol and reduced cortisol reactivity in a lab stress test. The study used a specific extract (Holixer) and was industry-funded, so results with other products may differ.

Pros

Gentle traditional adaptogen
Also studied for sleep quality
Widely available

Cons

Not the exact extract used in the main study
Evidence still limited

BEST FOR STRESS-RELATED FATIGUE

NOW Foods Rhodiola 500 mg

Rhodiola rosea is an adaptogen studied for fatigue and burnout. In a 2009 trial in people with stress-related fatigue, a standardized rhodiola extract improved fatigue and lowered the cortisol response to waking.

Pros

Studied for burnout fatigue
Usually not sedating
Affordable

Cons

Can feel stimulating; take in the morning
Not suitable for everyone, including some people with bipolar disorder

BEST FOR EXERCISE AND ACUTE STRESS

Jarrow Formulas PS100 Phosphatidylserine

Phosphatidylserine is a fat found in cell membranes. In a small 2008 study, 600 mg a day for 10 days lowered peak cortisol after exercise by about 39% compared with placebo. Evidence is limited to small studies.

Pros

Studied for cortisol after physical and mental stress
Well-known brand

Cons

Studied doses need several capsules
Small evidence base
Soy-derived

BEST OMEGA-3 FISH OIL

Nordic Naturals Ultimate Omega

In a 2021 trial of 138 middle-aged and older adults, 2.5 g a day of omega-3s for four months led to about 19% lower cortisol during a stress test than placebo. Omega-3s also support heart and brain health.

Pros

Concentrated EPA and DHA
Third-party tested by the brand
Lemon flavour reduces fishy taste

Cons

Studied dose needs several softgels
May interact with blood thinners

BEST FOR CALM WITHOUT DROWSINESS

NOW Foods L-Theanine 200 mg

L-theanine is an amino acid found in green tea. Studies suggest 200 mg a day may reduce stress-related symptoms and improve sleep quality in stressed adults, without causing drowsiness. Effects on cortisol are less consistent.

Pros

Calm focus without sleepiness
Can be taken day or evening
Affordable

Cons

Evidence for lowering cortisol is mixed
Effects are subtle for some people

Quick comparison

Strongest evidence for cortisol: ashwagandha.
Promising, smaller studies: holy basil, rhodiola, phosphatidylserine, omega-3.
For calm without drowsiness: L-theanine.
For evening relaxation: magnesium glycinate. See our magnesium supplement guide.

Safety: who should be careful

Pregnancy and breastfeeding: avoid herbal adaptogens such as ashwagandha, rhodiola and holy basil unless your doctor approves.
Thyroid or autoimmune conditions: ashwagandha is not recommended.
Medicines: ashwagandha, rhodiola and holy basil may interact with diabetes, blood pressure, thyroid, sedative and immune-suppressing medicines. Fish oil and phosphatidylserine may add to the effect of blood thinners.
Liver: rare cases of liver injury have been reported with ashwagandha. Stop and see a doctor if you notice yellow skin or eyes, dark urine or abdominal pain.
Bipolar disorder: rhodiola may not be suitable.
Very high cortisol from a medical condition such as Cushing’s syndrome needs medical treatment, not supplements.

Keep reading

Frequently asked questions

What is the best supplement to lower cortisol?

Ashwagandha has the most research for lowering cortisol and perceived stress, especially standardized root extracts like KSM-66. Talk to your doctor before starting it.

How long do cortisol supplements take to work?

Most studies measured results after 4 to 8 weeks of daily use.

Can I take ashwagandha and magnesium together?

Many people do, and there is no known direct interaction, but check with your doctor or pharmacist, especially if you take other medicines.

Do cortisol supplements help with belly fat?

They may help indirectly by reducing stress and improving sleep, but no supplement replaces a calorie deficit, regular activity and good sleep for losing belly fat.

Is it safe to take cortisol supplements long term?

Long-term safety is not well studied for most of these. Ashwagandha is considered possibly safe for up to about 3 months. Use them with medical advice.

Sources

This article is for general information only and is not medical advice. See our Medical Disclaimer.