Can I Take Ashwagandha with Evenity (Romosozumab)?

What Is Romosozumab (Evenity) and How Does It Work?

Romosozumab is a monoclonal antibody that binds and inhibits sclerostin, a glycoprotein produced by osteocytes that normally suppresses bone formation. Blocking sclerostin simultaneously increases bone formation and decreases bone resorption, a dual effect not seen with bisphosphonates or denosumab. The FDA approved Evenity in April 2019 for postmenopausal women with osteoporosis at high fracture risk, defined as a prior osteoporotic fracture, a T-score < -2.5, or multiple clinical risk factors.

Mechanism and Approved Use

Romosozumab works upstream of the Wnt signaling pathway. Sclerostin inhibits Wnt co-receptors LRP5 and LRP6 on osteoblasts; when romosozumab blocks sclerostin, Wnt signaling is restored and osteoblast activity accelerates. The FRAME trial (N=7,180) showed that 12 months of romosozumab 210 mg monthly reduced new vertebral fractures by 73% compared with placebo (P<0.001) [1]. Bone mineral density (BMD) at the lumbar spine increased 13.3% from baseline versus 0.0% for placebo at 12 months.

The Cardiovascular Safety Flag

Evenity carries a boxed warning. Patients who have experienced a myocardial infarction or stroke within the preceding 12 months should not receive the drug. The ARCH trial (N=4,093) found a higher rate of serious cardiovascular events with romosozumab versus alendronate (2.5% vs. 1.9%) over the active treatment period [2]. Any supplement that independently affects cardiovascular risk, blood pressure, or inflammatory markers warrants additional scrutiny in this population.

What Is Ashwagandha and Why Do Osteoporosis Patients Use It?

Ashwagandha (Withania somnifera) is a root extract used in Ayurvedic medicine for stress reduction, physical endurance, and hormonal support. Patients with osteoporosis often turn to it because of claims that it supports bone density, reduces cortisol (which accelerates bone loss at chronically elevated levels), and raises testosterone or DHEA in aging adults.

Active Compounds

The primary active constituents are withanolides, a class of steroidal lactones. Withaferin A and withanolide D are the most studied. Standardized extracts like KSM-66 and Sensoril typically contain 5% and 10% withanolides, respectively. Most clinical trials use 300 to 600 mg of root extract twice daily.

Why Osteoporosis Patients Reach for It

Chronic elevation of cortisol, as seen in hypothalamic-pituitary-adrenal (HPA) axis dysregulation, accelerates osteoclast activity and suppresses osteoblast differentiation, contributing directly to bone loss [3]. Ashwagandha has been shown to reduce serum cortisol. A double-blind, randomized, placebo-controlled trial (N=64) published in Medicine found that 300 mg of ashwagandha root extract twice daily for 60 days reduced morning serum cortisol by 27.9% versus 7.9% in the placebo group (P<0.001) [4]. Patients naturally equate cortisol reduction with bone protection, making the combination appealing.

Is There a Direct Drug Interaction Between Ashwagandha and Romosozumab?

No published pharmacokinetic interaction study exists between ashwagandha and romosozumab. That absence of evidence is not evidence of absence. The interaction concern is pharmacodynamic rather than metabolic.

Why There Is No Pharmacokinetic Concern

Romosozumab is a monoclonal antibody (IgG2 subclass) with a molecular weight of approximately 136 kDa. Monoclonal antibodies are not metabolized by cytochrome P450 (CYP) enzymes. They are cleared through proteolytic catabolism in the reticuloendothelial system. Ashwagandha withanolides are metabolized primarily via CYP3A4 and CYP2D6 [5]. Because romosozumab bypasses these enzymatic pathways entirely, ashwagandha cannot meaningfully alter its clearance, half-life (approximately 6.4 days), or plasma exposure.

Where the Pharmacodynamic Overlap Lives

Three overlapping physiological pathways create theoretical interaction risk even without shared CYP metabolism.

1. Cortisol suppression and Wnt signaling. Glucocorticoid excess suppresses Wnt pathway activity, which is the same pathway romosozumab activates. Ashwagandha's documented cortisol-lowering effect could theoretically augment the net pro-osteoblastic signal. This would be an additive benefit rather than an adverse interaction, though no trial has tested this combination.

2. Thyroid hormone modulation. Ashwagandha increases serum triiodothyronine (T3) and thyroxine (T4) in some subjects. A randomized trial (N=50) found that 600 mg/day of ashwagandha root extract for 8 weeks significantly increased T4 levels (P<0.05) compared with placebo [6]. Thyroid hormones regulate bone turnover directly. Hyperthyroid states accelerate bone resorption, which would work against romosozumab's anti-resorptive component. Patients with subclinical hypothyroidism on levothyroxine who add ashwagandha may see TSH suppression, inadvertently shifting toward a state that opposes bone formation.

3. Androgenic effects and bone. Ashwagandha raises serum testosterone and DHEA-S in several trials. A randomized, double-blind trial in healthy men (N=57) found that 600 mg/day KSM-66 for 8 weeks increased serum testosterone by 14.7% compared with 2.5% for placebo (P<0.05) [7]. Testosterone and its aromatized product estradiol are key regulators of bone remodeling. Whether a modest testosterone increase meaningfully supplements romosozumab's bone-anabolic effect is unknown, but it adds a variable that clinicians should track.

Monitoring Recommendations When Combining Both

Romosozumab already requires baseline and follow-up laboratory monitoring. Adding ashwagandha introduces additional variables. Below is a practical monitoring framework.

Baseline Tests Before Starting Romosozumab

Patients should have the following checked before the first injection:

• Serum calcium and 25-hydroxyvitamin D (hypocalcemia is a contraindication; correct deficiency before starting)
• TSH and free T4 (ashwagandha's thyroid effects make a baseline essential)
• Bone-turnover markers: procollagen type 1 N-terminal propeptide (P1NP) for formation; C-terminal telopeptide (CTX) for resorption
• Serum testosterone and DHEA-S if relevant to the patient's clinical picture

Monitoring During the 12-Month Course

At months 3, 6, and 12:

• Serum calcium (romosozumab increases calcium demand; hypocalcemia risk persists throughout therapy)
• TSH and free T4 (monthly if any change in levothyroxine dose or symptoms of thyroid dysfunction appear)
• P1NP and CTX to confirm anabolic response; expected P1NP rise of 60 to 70% above baseline within the first 3 months [1]
• Blood pressure, particularly in patients with pre-existing cardiovascular risk, given Evenity's boxed warning

A TSH shift above 4.0 mIU/L or below 0.4 mIU/L after starting ashwagandha warrants prompt evaluation and possible ashwagandha dose reduction or discontinuation. Do not adjust romosozumab dosing based on TSH alone.

What to Do If You Are Already Taking Both

If a patient is already taking ashwagandha when Evenity is prescribed, the clinician should:

1. Document the brand, dose, and standardization level of the ashwagandha product.
2. Obtain the baseline labs listed above before the first injection.
3. Schedule a 6-week follow-up lab check rather than waiting until month 3.
4. Review any concurrent medications (particularly levothyroxine, immunosuppressants, or sedative-hypnotics) because ashwagandha may potentiate CNS depressants and alter thyroid replacement requirements.

There is no published clinical reason to discontinue ashwagandha solely because of romosozumab use, provided thyroid status is normal and cardiovascular risk is acceptable.

Cortisol, Bone Loss, and Where Ashwagandha Fits

Chronic hypercortisolemia is among the most recognized secondary causes of osteoporosis. Glucocorticoid-induced osteoporosis (GIOP) accounts for up to 20% of all osteoporosis cases in some registry analyses [3]. The mechanism involves direct suppression of osteoblast proliferation and differentiation, increased RANKL expression (which activates osteoclasts), and reduced intestinal calcium absorption.

Ashwagandha's Evidence on HPA Regulation

The Medicine trial cited earlier (N=64) documented not only a 27.9% cortisol reduction but also improvements in perceived stress scores, serum testosterone, and general well-being [4]. A separate 60-day trial (N=60) using a higher-concentration ashwagandha extract (Sensoril, 250 mg twice daily) confirmed significant reductions in the stress biomarker C-reactive protein (CRP) and cortisol, with a mean cortisol decrease of 22.2% (P<0.05) [8].

Does Lower Cortisol Strengthen Romosozumab's Effect?

No trial has tested this directly. Theoretically, reducing one of the primary suppressors of osteoblast function while simultaneously activating the Wnt pathway with romosozumab could produce an additive effect on bone formation. The 2023 American Association of Clinical Endocrinology (AACE) clinical practice guideline for osteoporosis management notes that "secondary causes of bone loss should be identified and treated concurrently with pharmacologic therapy" [9]. Addressing HPA dysregulation through cortisol reduction, whether pharmacologic or via an evidence-supported supplement, aligns with that recommendation.

The AACE guideline does not specifically endorse ashwagandha. Clinicians should treat this as a hypothesis, not a proven co-benefit.

Ashwagandha and Thyroid Function: A Closer Look

The thyroid connection is the most clinically actionable concern for patients on romosozumab.

How Ashwagandha Affects Thyroid Hormones

The 8-week randomized trial by Sharma et al. (N=50) found statistically significant increases in both T3 and T4 with 600 mg/day ashwagandha, while TSH trended downward [6]. The proposed mechanism involves withanolides stimulating thyroid peroxidase activity or modulating the hypothalamic-pituitary-thyroid axis directly, though the precise pathway remains under investigation.

Why This Matters for Bone

Overt hyperthyroidism increases bone turnover markedly. Elevated T3 directly stimulates osteoclast activity via thyroid hormone receptors expressed on bone cells. Even a subclinical TSH suppression to below 0.1 mIU/L doubles the 10-year fracture risk in older women, according to a meta-analysis in Annals of Internal Medicine [10]. Patients taking romosozumab for fracture prevention would undermine the drug's benefit if ashwagandha simultaneously drives thyroid-mediated resorption.

Practical Guidance for Thyroid Management

Patients already on levothyroxine are at higher risk for this dynamic. Ashwagandha may reduce the required levothyroxine dose in patients with autoimmune hypothyroidism, a beneficial effect in isolation, but one that requires re-titration under physician supervision. Check TSH 6 weeks after introducing or changing the dose of ashwagandha in any patient on thyroid hormone replacement.

Bone-Specific Evidence for Ashwagandha

Does ashwagandha independently support bone density? Some preclinical data suggest yes, but human trial evidence is limited and should not be used to justify replacing or delaying pharmacologic treatment like romosozumab.

Animal and In Vitro Data

Withaferin A has been shown to inhibit osteoclastogenesis in mouse models by suppressing NF-kB signaling, the same pathway that RANKL activates to drive resorption [11]. Withanolide D promoted osteoblast differentiation in vitro in MC3T3-E1 cells. These are mechanistically interesting findings, but extrapolating murine cell-culture results to a human with a T-score of -3.2 would be clinically inappropriate.

Human Data

A 2016 randomized trial in perimenopausal women (N=91) found that 500 mg/day of ashwagandha root extract for 8 weeks significantly improved musculoskeletal strength but did not measure BMD by DEXA [12]. No published randomized controlled trial has measured DEXA-confirmed BMD change attributable to ashwagandha alone in postmenopausal women. Until that evidence exists, ashwagandha cannot replace, shorten, or substitute for the 12-month Evenity course.

Dose-Separation Windows and Practical Administration

Because romosozumab is a subcutaneous injection given once monthly at a clinic, not a daily oral medication, dose-separation windows are less relevant than for oral drugs competing for the same absorption pathway.

No Oral Absorption Competition

Monoclonal antibodies are not administered orally and are not absorbed through the GI tract. Ashwagandha taken orally has no opportunity to interfere with subcutaneous absorption of romosozumab at the injection site. Patients do not need to time ashwagandha doses around injection days.

Supplement Quality Considerations

Unregulated supplements can contain undisclosed ingredients. Patients should use ashwagandha products with third-party certification (NSF International, USP Verified, or Informed Sport). Contaminated products that contain heavy metals, undisclosed androgens, or thyroid-active compounds could introduce interactions not attributable to ashwagandha itself. This is especially relevant in the context of Evenity's cardiovascular boxed warning.

Special Populations

Patients on Immunosuppressants

Romosozumab is occasionally used in transplant recipients or patients with inflammatory bone disease who are also on corticosteroids or other immunosuppressants. Ashwagandha has mild immunomodulatory properties. While this has not produced documented problems in clinical trials, clinicians should review the full medication list before green-lighting ashwagandha in immunocompromised patients.

Patients with Subclinical Cardiovascular Disease

Ashwagandha modestly reduces blood pressure in some trials, with a 2019 study (N=60) showing a 5.5 mmHg reduction in systolic BP after 8 weeks [8]. Given Evenity's boxed warning for cardiovascular events, any additive hypotensive effect in a patient who is also on antihypertensives should be tracked. This is a monitoring issue, not a contraindication.

Men with Osteoporosis

The FDA approved romosozumab for men at high fracture risk in 2020. Ashwagandha's testosterone-raising effect may be more clinically significant in men. A 14.7% increase in testosterone could theoretically enhance the anabolic environment for bone formation, but no study has examined this pairing. Men on Evenity who add ashwagandha should have testosterone, free testosterone, and hematocrit checked at baseline and at 3 months because supraphysiologic testosterone elevates erythropoiesis.

What Clinicians and Guidelines Say

The AACE 2023 osteoporosis guideline states: "Patients receiving bone-active therapies should be evaluated for secondary causes of bone loss and for medications and supplements that may interfere with the pharmacologic treatment's mechanism of action" [9].

The Endocrine Society's 2019 clinical practice guideline on osteoporosis in men notes that bone-anabolic therapy should not be delayed or modified based on unverified supplement claims, and that "the treatment window for romosozumab is fixed at 12 monthly doses with no provision for extension" [13].

No guideline from AACE, the Endocrine Society, or the American Society for Bone and Mineral Research (ASBMR) specifically addresses ashwagandha co-administration with any bone-anabolic agent. That gap reflects the limited clinical trial data, not an implicit endorsement of safety.

Summary of Risk Level by Interaction Type

| Interaction Type | Mechanism | Risk Level | Action | |---|---|---|---| | Pharmacokinetic (CYP) | None (romosozumab bypasses CYP) | None | No action needed | | Thyroid hormone elevation | Ashwagandha may raise T3/T4 | Moderate | Monitor TSH/T4 at baseline and month 3 | | Cortisol reduction | May augment osteoblast activity | Low / potentially additive benefit | Monitor bone-turnover markers | | Testosterone increase | May enhance anabolic environment | Low / potentially additive benefit | Monitor in men; check hematocrit | | Cardiovascular (BP) | Ashwagandha may lower BP | Low in most patients | Monitor BP; flag in cardiac-risk patients | | Supplement contamination | Undisclosed active ingredients | Variable | Use NSF/USP-certified products only |