Ashwagandha Side Effects: What to Know Before You Take It

Ashwagandha (Withania somnifera), also known as Indian ginseng, has become one of the most popular herbal supplements on the market. Used in ayurvedic medicine for centuries, this adaptogenic herb is celebrated for its ability to reduce stress, support hormonal balance, and improve energy levels. But like any supplement, ashwagandha comes with potential side effects that every user should understand before starting a regimen.

This guide covers the full spectrum of ashwagandha side effects — from common and mild reactions to rare but serious concerns. Whether you're considering your first dose or have been supplementing for months, knowing what to watch for helps you use this herb safely and effectively.

Common Ashwagandha Side Effects

Most people tolerate ashwagandha well, especially at standard doses of 300–600mg daily. However, some users do experience mild side effects, particularly during the first few days of supplementation.

Digestive discomfort

The most frequently reported side effect is gastrointestinal upset. This can include nausea, stomach cramping, diarrhea, or loose stools. Taking your ashwagandha supplement with food rather than on an empty stomach typically resolves these issues. Root extract formulations like KSM-66 tend to be gentler on the stomach than whole root powder because the extraction process removes many of the compounds that irritate the digestive tract.

Drowsiness and sedation

Ashwagandha has calming properties that support sleep — but this same mechanism can cause daytime drowsiness in some users, particularly at higher doses. If you experience excessive sleepiness, try taking your dose in the evening instead of the morning. This side effect is generally dose-dependent and resolves with adjustment.

Headaches

Some users report mild headaches during the first week of supplementation. These are typically transient and resolve as your body adjusts. Staying well-hydrated and starting with a lower dose can help minimize this effect.

Ashwagandha and Thyroid Function

One of the most important considerations with ashwagandha is its effect on thyroid hormone levels. Multiple clinical trials have demonstrated that ashwagandha can increase thyroid hormone production, including both T3 and T4 levels. For people with hypothyroidism (underactive thyroid), this can be beneficial — but for those with an overactive thyroid (hyperthyroidism) or Graves' disease, ashwagandha could worsen symptoms.

If you take thyroid medications such as levothyroxine, ashwagandha may interfere with your medication's effectiveness by independently altering thyroid hormone levels. Always consult your healthcare provider before combining ashwagandha with any thyroid treatment. Regular thyroid panel monitoring is essential if you choose to supplement.

Ashwagandha Side Effects for Women

Women may experience unique side effects related to ashwagandha's hormonal activity. The herb influences estrogen, progesterone, and testosterone pathways, which means it can affect menstrual cycles, fertility, and hormone-sensitive conditions.

Menstrual changes

Some women report changes in their menstrual cycle when starting ashwagandha — including heavier periods, lighter periods, or shifts in cycle length. These changes typically stabilize within 2-3 cycles. If irregularities persist, discontinue use and consult your healthcare provider.

Pregnancy concerns

Ashwagandha is classified as potentially unsafe during pregnancy. Animal studies suggest it may have abortifacient properties at high doses, and there is insufficient human safety data. Most practitioners in both conventional and complementary and integrative health recommend avoiding ashwagandha entirely during pregnancy and breastfeeding.

Hormone-sensitive conditions

Women with hormone-sensitive conditions such as endometriosis, uterine fibroids, or hormone-receptor-positive breast cancer should exercise particular caution. Ashwagandha's ability to modulate hormone levels means it could theoretically worsen these conditions, though direct clinical evidence is limited.

Ashwagandha Side Effects for Men

Men generally tolerate ashwagandha well, and many of its studied benefits — including testosterone support and fertility enhancement — are specifically relevant to male health. However, there are a few considerations.

Testosterone elevation

While increased testosterone is often a desired effect, men with hormone-sensitive prostate conditions should be cautious. If you have a history of prostate cancer or elevated PSA levels, discuss ashwagandha with your doctor before supplementing.

Changes in libido

Most studies show ashwagandha increases libido and sexual function in men. However, a small number of users report the opposite effect, particularly at very high doses. This paradoxical response may be related to individual hormonal profiles.

Liver Safety and Ashwagandha

Recent case reports have raised concerns about ashwagandha-induced liver injury. The National Institutes of Health's LiverTox database now includes ashwagandha as a potential cause of drug-induced liver injury, with several documented cases of elevated liver enzymes and, in rare instances, jaundice.

These cases appear to be idiosyncratic — meaning they affect a very small number of people and aren't predictable based on dose alone. Risk factors may include pre-existing liver conditions, concurrent use of other hepatotoxic supplements or medications, and possibly genetic factors affecting drug metabolism.

To minimize risk, choose high-quality ashwagandha supplements from reputable manufacturers that provide third-party testing. Avoid exceeding recommended doses, and consider periodic liver function testing if you plan to use ashwagandha long-term.

Drug Interactions and Contraindications

Ashwagandha can interact with several classes of medications. The most significant interactions include:

Thyroid medications

As discussed, ashwagandha can increase thyroid hormones independently, potentially requiring dose adjustments of thyroid medications like levothyroxine or methimazole.

Mood and anxiety treatments

Ashwagandha has GABAergic activity, meaning it affects the same neurotransmitter pathways as benzodiazepines, barbiturates, and some antidepressants. Combining ashwagandha with mood and anxiety treatments may enhance sedative effects beyond what's intended. If you're taking SSRIs, SNRIs, or anti-anxiety medications, work closely with your healthcare provider when adding ashwagandha.

Immunosuppressants

Ashwagandha has demonstrated immunomodulatory properties in several studies. For people taking immunosuppressive drugs (organ transplant recipients, autoimmune disease patients on biologics), ashwagandha could potentially counteract the medication's intended effect.

Blood sugar medications

Ashwagandha may lower blood sugar levels. If you're taking diabetes medications or insulin, combining them with ashwagandha could cause hypoglycemia. Monitor your blood sugar more frequently if you decide to supplement.

Blood pressure medications

The herb may also lower blood pressure, which could compound the effects of antihypertensive medications. Monitor blood pressure regularly during initial supplementation.

Who Should Avoid Ashwagandha

Based on current evidence and clinical guidance from complementary and integrative health professionals, the following groups should avoid ashwagandha or use it only under direct medical supervision:

People with overactive thyroid conditions or Graves' disease should not take ashwagandha due to its thyroid-stimulating effects. Pregnant and breastfeeding women lack sufficient safety data and should avoid supplementation. Anyone with active liver disease or a history of drug-induced liver injury should exercise extreme caution. People scheduled for surgery should discontinue ashwagandha at least two weeks beforehand, as it may affect anesthesia and blood clotting. Those with autoimmune conditions such as lupus, rheumatoid arthritis, or multiple sclerosis should consult their doctor first, since ashwagandha's immune-stimulating properties could worsen flare-ups.

How to Minimize Side Effects

If you decide ashwagandha is right for you, these strategies can help minimize the risk of adverse effects:

Start low and go slow. Begin with 150–300mg daily and increase gradually over 2-3 weeks. This gives your body time to adjust and helps you identify your optimal dose without overshooting.

Take it with food. This simple step eliminates the most common side effect — digestive discomfort. A small meal or snack is sufficient.

Choose standardized extracts. Root extracts standardized to withanolide content (like KSM-66 at 5% withanolides) provide consistent dosing and tend to produce fewer side effects than raw powder. Tribe Organics Ashwagandha KSM-66 delivers 600mg of clinically studied root extract per serving.

Cycle your use. Many practitioners recommend taking ashwagandha for 2-3 months, then taking a 2-4 week break. This cycling approach may reduce the risk of tolerance and long-term side effects.

Monitor and communicate. Keep your healthcare provider informed about all herbal supplements you take, especially if you're on prescription medications. Report any unusual symptoms promptly.

What the Clinical Research Says

Systematic reviews of clinical trials involving ashwagandha consistently find that the herb is well-tolerated in healthy adults at doses up to 600mg daily for periods of 8-12 weeks. Most clinical trials report adverse event rates comparable to placebo groups, suggesting that mild side effects occur at similar rates whether you take ashwagandha or not.

However, it's worth noting that most published trials involve relatively small sample sizes and short durations. Long-term safety data (beyond 12 months) is limited, which is why cycling and regular check-ins with your healthcare provider remain important.

Related reading: Ashwagandha: A Definitive Guide — your complete resource for ashwagandha benefits, dosage, and usage.

Frequently Asked Questions

Can ashwagandha cause weight gain?

Ashwagandha does not directly cause weight gain. In fact, research suggests it may support healthy weight management by reducing cortisol-driven fat storage. However, improved appetite from reduced stress could lead to increased calorie intake in some individuals.

Does ashwagandha cause hair loss?

There is no evidence that ashwagandha causes hair loss. On the contrary, by supporting thyroid function and reducing stress-related cortisol, ashwagandha may actually benefit hair health in some users.

Can you take ashwagandha every day?

Most studies use daily dosing for 8-12 weeks with good safety profiles. However, many complementary and integrative health practitioners recommend periodic breaks (cycling) to maintain effectiveness and reduce any potential for long-term accumulation effects.

What happens if you take too much ashwagandha?

Doses exceeding 1,200mg daily have not been well-studied and may increase the risk of gastrointestinal upset, excessive sedation, and thyroid disruption. Stick to established dosing ranges and follow the manufacturer's recommendations on your ashwagandha supplement label.

Prefer a gummy form? Try this guide to ashwagandha gummies.