Can You Take Tongkat Ali and Ashwagandha Together?

Taking tongkat ali and ashwagandha together is generally considered safe, and no published research has identified a dangerous interaction between the two herbs. They share some overlapping effects on stress hormones and testosterone, but they work through different enough pathways that combining them is unlikely to produce redundant or conflicting activity. That said, the combination has not been studied directly in clinical trials, so the evidence supporting their joint use is extrapolated from studies on each herb individually.

How Their Mechanisms Overlap and Differ

Both tongkat ali and ashwagandha are classified as adaptogens, meaning they help the body manage stress. But they arrive at that result through somewhat different biological routes, which is actually the main argument for stacking them rather than choosing one or the other.

Tongkat ali (Eurycoma longifolia) appears to act most directly on the hormonal side of the stress equation. In a trial of moderately stressed adults, daily supplementation reduced salivary cortisol by about 16% and raised testosterone status by roughly 37%.¹ A separate pilot study in older men and women found significant increases in both total and free testosterone concentrations along with improved muscular force, with the rise in free testosterone in women linked to a drop in sex hormone-binding globulin.²

Ashwagandha (Withania somnifera) works more broadly on what researchers call the hypothalamic-pituitary-adrenal axis, the chain of hormonal signals that governs your body’s stress response. A placebo-controlled trial found that ashwagandha reduced morning cortisol and DHEA-S levels, suggesting it makes the stress response less reactive to triggers rather than simply counteracting cortisol after the fact.³ Another randomized trial confirmed a reduction in morning salivary cortisol and also noted an increase in urinary serotonin, pointing to mood-regulating effects beyond the stress-hormone axis alone.⁴

Both lower cortisol. Both support testosterone. But tongkat ali’s primary reputation is as a more direct testosterone and libido enhancer, while ashwagandha has a wider portfolio that includes anxiety reduction, sleep support, and serotonin modulation. When people stack them, the logic is that tongkat ali handles the hormonal lift while ashwagandha provides a broader stress-buffering foundation.

What Each Brings to Testosterone

One of the most common reasons people consider combining these herbs is testosterone support, so it is worth looking at what each actually does on its own.

Tongkat ali’s testosterone data is the more dramatic of the two. The 37% increase in testosterone status observed in moderately stressed subjects is a frequently cited figure, though it is worth noting that the study population was stressed adults, not hypogonadal men, and the measurement was salivary testosterone, not serum.¹ The mechanism seems to involve freeing up testosterone that is already circulating rather than stimulating production from scratch, which is why the pilot study in seniors found a notable drop in sex hormone-binding globulin alongside the testosterone rise.²

Ashwagandha’s testosterone effects are more modest but still meaningful. A pilot study in oligospermic males found a 17% increase in serum testosterone and a 34% increase in luteinizing hormone (the upstream signal that tells the testes to produce testosterone) after treatment with ashwagandha root extract.⁵ A crossover study in overweight, aging men found an 18% rise in DHEA-S and a roughly 15% rise in testosterone during ashwagandha supplementation compared to placebo.⁶

Since tongkat ali seems to work partly by reducing the protein that binds up free testosterone while ashwagandha may boost the upstream hormonal signal for testosterone production, the two herbs could theoretically complement each other. Nobody has tested that hypothesis head-to-head, but it is biologically plausible enough that the pairing has become popular in the supplement world.

Exercise Performance and Physical Outcomes

If you train regularly, the combination holds some appeal beyond hormones. Ashwagandha has a growing body of evidence around aerobic and strength outcomes. A systematic review and meta-analysis found that ashwagandha supplementation significantly improved VO2max (a measure of aerobic capacity) in both athletes and non-athletes.⁷ An eight-week placebo-controlled trial confirmed this, finding that ashwagandha led to a 9.5% increase in VO2max in males and 7% in females who were doing resistance training, along with statistically significant improvements in bench press and leg press performance.⁸

Tongkat ali’s exercise data is thinner but still relevant. The pilot study in older adults showed improved muscular force alongside the hormonal changes.² Its stress-reduction profile, including lower cortisol and improved mood states like reduced tension and anger, could also indirectly support training by improving recovery and consistency.¹ Chronically elevated cortisol works against muscle protein synthesis and promotes fat storage, so any supplement that chips away at cortisol may indirectly support body composition when combined with exercise.

For someone stacking both, ashwagandha brings the more robust data for direct strength and endurance gains, while tongkat ali contributes more to the hormonal environment that supports those gains over time. Neither is a substitute for actual training, but the combination is one of the more evidence-backed herbal stacks for people who are already exercising.

Sleep and Mood Benefits

Ashwagandha has an advantage here that tongkat ali does not share. Multiple preclinical studies have found that ashwagandha promotes sleep through the GABAergic system. One study showed that an amylase-treated ashwagandha extract increased GABA content in the brain along with expression of GABA and serotonin receptors, and that the extract exhibited sleep-promoting activity by binding to various GABA receptor sites.⁹ A separate study confirmed these findings, showing increased expression of GABA receptors and histamine H3 receptors, along with induction of sleep and increases in non-REM sleep and slow-wave cycles.¹⁰

Tongkat ali does not appear to have these sleep-promoting properties. Its mood effects are more about daytime stress management: the reductions in tension, anger, and confusion reported in the supplementation trial suggest it may help you feel calmer and more focused during waking hours, but there is no evidence it helps you fall asleep or stay asleep.¹

This natural division is actually useful for timing. Some people take tongkat ali in the morning (when its cortisol-lowering and energy-related effects are most useful) and ashwagandha in the evening (when its GABA-mediated calming effects can support sleep). There is no hard clinical data dictating this split, but it fits the pharmacological profile of each herb reasonably well, and many users report good results with that schedule.

Safety Concerns Worth Knowing About

Most clinical trials of both herbs report mild or no side effects. But when you combine two herbal supplements, the safety question gets more complex because each brings its own risks, and taking them together means accepting both.

Ashwagandha’s most concerning documented side effect involves the thyroid. A critical review of clinical and preclinical evidence noted that ashwagandha’s endocrine-modulating activity has been implicated in thyrotoxicosis and adrenal suppression.¹¹ In one case report, a 73-year-old woman who had been self-treating hypothyroidism with ashwagandha for two years presented with supraventricular tachycardia and dangerously low TSH levels consistent with hyperthyroidism.¹² If you have any thyroid condition, or if you are taking thyroid medication, ashwagandha deserves a conversation with your doctor before you start.

Tongkat ali’s safety profile has been generally favorable in studies, but a case report described a 47-year-old man who developed acute liver injury after starting tongkat ali supplementation. He presented with jaundice and elevated liver enzymes, and improved after discontinuing the supplement. The authors noted this was the first reported case of its kind in the literature, but emphasized that the risk may increase when someone is consuming multiple supplements simultaneously.¹³

That last point is directly relevant to combining the two. When you stack supplements, you increase the total metabolic load on your liver. Neither ashwagandha nor tongkat ali is considered hepatotoxic at standard doses in healthy adults, but if you are already taking other medications or supplements that stress the liver, adding two more compounds is worth thinking about carefully. This is especially true because herbal supplement interactions with conventional drugs have mostly only been studied in animal or in vitro models, not in human trials.

The Product Quality Problem

Here is something the “can I take these together” conversation usually skips: whether what you are actually taking is what the label says. This matters more for tongkat ali than for most supplements. A study using DNA barcoding and chemical analysis to test tongkat ali herbal products found that only 37% of tested products were authentic. Twenty-seven percent were adulterated with other plant species. Even some products that passed DNA identification as the right species did not contain the expected chemical compounds on further analysis.¹⁴

This has real implications for safety. If you buy a tongkat ali product that turns out to be adulterated with an unknown plant, the safety data from clinical trials of genuine Eurycoma longifolia does not apply to what you are taking. The liver injury case report noted that the patient was consuming a supplement whose actual contents could not be independently verified. When you are stacking two herbal products, the adulteration risk effectively doubles because you are trusting two supply chains instead of one.

Ashwagandha products tend to be more standardized, particularly those labeled with a recognized extract name (KSM-66 and Sensoril are the two most commonly used in clinical research). For tongkat ali, look for products that specify standardization to eurycomanone content, and consider sourcing from Malaysian-origin brands, since Malaysia has the most developed quality-control infrastructure for tongkat ali. None of this guarantees purity, but it improves your odds.

Dosing and Practical Considerations

Because no clinical trial has tested the combination directly, there are no evidence-based dosing protocols for the stack. What most practitioners and informed users do is take each supplement at its individually studied dose:

Tongkat ali: most studies have used 200 to 400 mg per day of a standardized water extract, typically taken in the morning.
Ashwagandha: most clinical trials use 300 to 600 mg per day of a standardized root extract, with some studies going up to 1,000 mg. The calming effects make evening dosing a reasonable option, though many trials dosed it in the morning or split across morning and evening.

Starting each supplement separately before combining them is a common-sense approach. Take one for a couple of weeks, note any side effects, then add the second. If something goes wrong after introducing the second herb, you know which one to blame. This sounds basic, but the liver injury case report illustrates why it matters: the patient was taking multiple agents, which made it harder to isolate the cause initially.

Cycling is another common practice. Some people take tongkat ali five days on, two days off, or run four-week-on, one-week-off cycles. The rationale is to prevent receptor desensitization, though there is no published human data showing that cycling is necessary or beneficial for either herb. It is a precautionary habit borrowed from other supplement categories rather than something the research specifically supports.

Who Should Be Cautious

A few groups should think twice before combining these herbs, or before taking either one at all:

People with thyroid conditions: ashwagandha’s thyroid-stimulating activity makes it risky for anyone with hyperthyroidism or anyone on thyroid medication without medical supervision.
People with liver disease or on hepatotoxic medications: the rare but documented case of tongkat ali-related liver injury suggests extra caution if your liver is already compromised.
People on blood thinners or blood pressure medications: both herbs can influence hormonal and cardiovascular parameters, and herbal-drug interactions in this space are poorly studied in humans.
Women who are pregnant or breastfeeding: neither herb has been studied for safety in pregnancy, and both have hormonal activity that makes caution appropriate.
People with hormone-sensitive cancers: any supplement that raises testosterone, DHEA-S, or other sex hormones could theoretically accelerate hormone-sensitive tumors. The clinical significance of the modest hormonal shifts these herbs produce is unknown in this context, but most oncologists would advise against it.

What Users Actually Report

An exploratory survey of 182 men who used testosterone-boosting supplements found that roughly two-thirds perceived they had gained expected benefits, including changes in body composition, energy, and libido. About a quarter reported mild side effects. The researchers noted that most respondents were also making other lifestyle changes and taking other supplements, and very few had any objective measurement of their hormone levels before and after.¹⁵

This is a useful reality check. The people most enthusiastic about herbal testosterone stacks are also the people most likely to be exercising more, sleeping better, and making dietary changes simultaneously. Disentangling the supplement’s contribution from the lifestyle overhaul is genuinely difficult without controlled trials. That does not mean the herbs do nothing. The individual clinical trial data shows real hormonal and physiological shifts. But the dramatic before-and-after stories you encounter online almost certainly overstate what the supplements alone are doing.

For the average healthy adult considering this stack, the honest picture is: both herbs have meaningful individual evidence for stress reduction, modest testosterone support, and some physical performance benefits. Combining them is biologically plausible and probably safe at standard doses. But nobody has proven that taking both is better than taking either one alone, and the biggest variable in how you feel will still be whether you are sleeping, exercising, and managing stress through non-supplement means.