The herb Withania somnifera, commonly known as Ashwagandha, is an adaptogen revered in Ayurvedic practice for its ability to promote balance within the body’s stress response systems. It is widely sought out for its calming properties, which are frequently linked to reducing anxiety and lowering elevated cortisol levels. This traditional usage has driven its popularity as a modern supplement for managing stress. However, some users seeking tranquility instead experience agitation or a feeling of being “wired.” This unexpected reaction, where a calming agent causes the opposite effect, is a real phenomenon for a subset of individuals.
Is Irritability a Known Side Effect
The direct answer to whether Ashwagandha can cause irritability is yes, although it is considered an uncommon, paradoxical reaction. This side effect often manifests as a state of heightened emotional sensitivity, restlessness, or agitation. Users frequently describe feeling “wired but tired,” where the mind is overstimulated while the body remains exhausted. This emotional volatility can be frustrating, especially since the herb is taken specifically to promote a sense of calm.
For some sensitive individuals, this agitation can also lead to difficulty sleeping or waking up with racing thoughts. This reaction appears to be an individual sensitivity to the herb’s powerful influence on neurochemistry, contrasting with more common, transient side effects like mild drowsiness or loose stools.
Underlying Biological Mechanisms
The paradoxical agitation is rooted in Ashwagandha’s complex interaction with hormonal and neurotransmitter pathways. One primary mechanism involves the herb’s influence on the hypothalamic-pituitary-adrenal (HPA) axis, which governs the body’s stress response. Ashwagandha is effective at reducing the stress hormone cortisol. For individuals who already have low or irregular cortisol patterns, or those with highly sensitive systems, this drop can be too rapid or too severe. This sudden hormonal shift can disrupt the body’s established rhythm, manifesting as temporary agitation or a feeling of being unsettled.
The herb also possesses a notable influence on the thyroid axis, which can contribute to a hyper-stimulated state. Research indicates that Ashwagandha can potentially increase levels of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). For a person with a pre-existing thyroid sensitivity or hyperthyroidism, this stimulation can mimic the symptoms of an overactive thyroid. These symptoms include anxiety, increased heart rate, and pronounced irritability.
Ashwagandha also influences the brain’s main inhibitory neurotransmitter, gamma-aminobutyric acid (GABA). The herb’s compounds appear to mimic or enhance GABA’s action, which is typically beneficial for anxiety reduction. However, a sudden or excessive influence on these receptors can cause a paradoxical or rebound effect in a small portion of the population. This unexpected neurochemical shift can potentially trigger the very agitation the herb is meant to quell.
Modifying Dosage and Supplement Quality
Individuals who experience irritability should first consider adjusting their dosage or timing. The standard effective dose for stress reduction is often between 250 mg and 600 mg of a high-concentration extract per day, but starting with a very low dose is advisable to gauge individual tolerance. If taking a single high dose, dividing it throughout the day or reducing the total amount can mitigate the sudden impact on the HPA axis. Some users find that taking the herb in the morning is too stimulating, while others find an evening dose contributes to sleep-interrupting restlessness.
Interactions and Quality
It is important to consider potential interactions with other substances that affect the nervous system. Ashwagandha’s calming effects can be counteracted or amplified by stimulants like caffeine, which can contribute to the unpleasant “wired but tired” feeling. Individuals should evaluate their consumption of coffee, energy drinks, and other supplements that affect cortisol or thyroid function.
The quality and standardization of the supplement are also significant factors in managing side effects. The unpredictability of reactions can sometimes be traced to non-standardized extracts or inconsistent levels of active compounds known as withanolides. Opting for scientifically studied, standardized extracts, such as KSM-66 or Sensoril, ensures a more predictable concentration of the active ingredients. Users should look for products that confirm third-party testing to verify purity and potency.
If the symptoms of irritability, agitation, or restlessness persist even after adjusting the dose and checking for interactions, discontinuing use may be necessary. Because Ashwagandha has a powerful effect on the endocrine system, anyone experiencing severe or worsening symptoms should consult a healthcare provider, particularly if they have a pre-existing thyroid condition or are taking prescription medications.