Ashwagandha and immunity: can it strengthen defences

What the research says about ashwagandha and the immune system

Ashwagandha is widely marketed as an immune supporter. The evidence is more nuanced than the marketing. The 2021 Tharakan immunomodulatory trial showed measurable changes in immune cell markers. No high-quality trial has shown reduced infection rates or improved clinical outcomes in humans. Here is what the evidence actually shows and what it does not show.

1. Short-term immune marker changes are documented

The Tharakan 2021 trial (PMC8397213) randomised healthy adults to ashwagandha root and leaf extract or placebo for 30 days. The ashwagandha group showed significant increases in immunoglobulins (IgA, IgM, IgG, IgG2, IgG3, IgG4), cytokines (IFN-gamma, IL-4) and T cell markers (CD3+, CD4+, CD8+, CD19+, NK cells) compared with placebo. The shifts in markers are real and measurable.

2. Marker changes are not the same as fewer infections

The Tharakan trial measured immune cell markers in healthy adults. It did not measure infection rates, illness duration, severity or any clinical outcome. Higher immunoglobulin counts in healthy people who do not get infections more often than the general population do not necessarily translate to fewer infections in the supplemented group. No high-quality trial has shown that ashwagandha reduces respiratory infection rates, shortens cold duration or prevents flu.

3. Stress reduction has a stronger evidence base for immunity

Chronic stress is one of the strongest documented suppressors of immune function. Cortisol elevation impairs T cell function, reduces natural killer cell activity and increases susceptibility to viral infections. Ashwagandha's stress-reducing effect (which is well documented) indirectly supports immune function through cortisol normalisation. This indirect pathway may be more meaningful than direct immunomodulation though it is also harder to measure.

4. Withaferin A has in vitro antiviral activity

Cell culture and animal studies show that withaferin A (a major withanolide in ashwagandha leaves) has antiviral activity against several viruses including herpes simplex and influenza in laboratory conditions. This work generated speculation about potential COVID-19 applications during the pandemic. None of this in vitro activity has translated into demonstrated clinical benefit in humans. Cell-culture activity rarely translates directly to whole-body therapeutic effect.

5. Things that do more for your immune system than ashwagandha

Adequate sleep (7 to 9 hours nightly) directly affects T cell function and antibody response to vaccination. Vitamin D sufficiency (above 50 nmol/L) supports immune function and is achievable through a 1000 to 2000 IU daily supplement in winter for UK adults. Vaccination including annual flu jab and COVID boosters where eligible. Not smoking. Regular moderate exercise. Limiting alcohol. These interventions have far stronger evidence bases than ashwagandha for actually reducing infection rates.

How to use ashwagandha for immune support sensibly in five steps

If you are using ashwagandha for general wellness with immune support as one motivation, here is how to keep expectations realistic and combine the supplement with interventions that have stronger evidence for actually reducing illness.

Step 1. Address the basics first

Sleep 7 to 9 hours nightly. Maintain vitamin D sufficiency (consider 1000 to 2000 IU daily October to March for UK adults per Public Health England guidance). Get your flu vaccine if eligible. Wash hands. Do not smoke. Limit alcohol. These do more for your immune system than any supplement. Ashwagandha works best as an addition rather than a substitute for these basics.

Step 2. Use the standard 600 mg daily protocol

Take 300 mg of standardised root extract twice daily, totalling 600 mg per day. The Tharakan trial used a similar protocol. Higher doses do not produce significantly bigger immune marker changes but do increase side effect risk. Look for KSM-66 or Sensoril branded extracts at minimum 2.5 percent withanolides. Take with meals containing fat.

Step 3. Frame it as stress support not infection prevention

The strongest plausible immune benefit of ashwagandha is via stress reduction. People with high baseline stress have measurably suppressed immune function. Normalising that through cortisol reduction may produce indirect immune benefits. Marketing the supplement as direct immune protection overstates the evidence. The supplement is more honestly described as stress support that may have immune correlates.

Step 4. Do not skip vaccinations or medical care because you take ashwagandha

No supplement substitutes for evidence-based medical care. Vaccination has the strongest evidence base of any immune intervention for preventing specific infectious diseases. Antibiotics treat bacterial infections that supplements do not. Antiviral medications treat established viral infections far more effectively than supplements. If you develop a serious infection, see your GP rather than taking more supplements.

Step 5. Stop if you have or develop an autoimmune condition

Ashwagandha can stimulate immune activity which is unhelpful in autoimmune diseases where the immune system is already overactive against the body's own tissues. People with rheumatoid arthritis, lupus, multiple sclerosis, Hashimoto's thyroiditis or other autoimmune conditions should avoid ashwagandha. If you develop new joint pain, unexplained rashes or other autoimmune symptoms while taking the supplement, stop and see your GP.

For anyone using ashwagandha as part of a broader healthy lifestyle that also includes sleep, vitamin D, vaccination and other evidence-based practices, our Ashwagandha Gummies deliver the standardised root extract dose used in the clinical trials. Same active ingredient. Convenient daily format.

When ashwagandha is a problem

Ashwagandha at standard doses is generally well tolerated. The UK Food Standards Agency is currently reviewing ashwagandha food supplements. Stop the supplement and see your GP if any of the following apply.

• New or worsening autoimmune symptoms including joint pain, unexplained rashes, fatigue or new neurological symptoms. Ashwagandha can stimulate immune activity.
• Yellowing of skin or eyes, dark urine or right upper abdominal pain. These can signal liver injury which has been reported rarely (LiverTox 2024).
• Symptoms of thyroid overactivity such as palpitations, tremor or heat intolerance. Ashwagandha can raise thyroid hormone levels.
• Taking immunosuppressant medication for organ transplant, autoimmune disease or other conditions. Ashwagandha may counteract immunosuppression.
• Severe or persistent infection. See your GP rather than relying on supplements. Some infections need antibiotics, antivirals or other specific medical treatment.

People with autoimmune conditions, those on immunosuppressant medication, those with active infections requiring medical treatment and pregnant women should not use ashwagandha for immune support. The supplement is not a substitute for vaccination or evidence-based medical care of infections.

More on ashwagandha and overall health

Immune effects connect to broader ashwagandha benefits. Common myths and misconceptions about ashwagandha covers exaggerated immune claims. Is ashwagandha safe covers safety including autoimmune considerations. And does ashwagandha work covers the broader evidence picture.