Everything Everywhere All at Once: Uncovering the Over-the-Counter Supplement in the Cancer Care Multiverse

Introduction

The use of over-the-counter (OTC) supplements has been found to be prevalent among patients with cancer, with studies estimating a range of 64–81% of patients reporting supplement use, often concurrently with active oncologic treatment.¹ Patients use supplements for various reasons, including managing treatment-related side effects, promoting general wellness, and as complementary or alternative treatments for their disease. Robust data supporting efficacy and benefit of supplements remains limited. However, some supplements (i.e. St. John’s Wort, turmeric) may alter drug metabolism, which may potentially compromise the efficacy or increase the toxicity of various oncologic treatments.^2-4 These risks are further compounded as patients often underreport supplement use to clinicians, often driven by the misconception that "natural" products are inherently safe.⁵ In parallel, rapid expansion of internet access and social media has facilitated widespread dissemination of health information which may often be inaccurate. Notably, an analysis of cancer-related treatment content with high engagement on social media found nearly one-third contained misinformation, with over 75% of those posts containing potentially harmful information.⁶

To navigate this complex landscape, clinicians have increasingly relied on resources like the Natural Medicines and Memorial Sloan Kettering Cancer Center (MSKCC)’s About Herbs databases to make evidence-based recommendations. Despite such tools, significant knowledge gaps persist among both patients and clinicians regarding safe use of supplements and strategies for facilitating open dialogue, particularly in a time where new anti-cancer therapies are constantly being brought to market alongside the multiple channels for information dissemination. Due to these issues, the HOPA Patient Outreach and Education Committee (POEC) embarked on a two-phase project that ultimately aims to better equip oncology pharmacists with tools to navigate these conversations with patients.

Methods

The first phase of this initiative involved development and distribution of a survey to assess current perspectives, clinical practices, and educational needs related to OTC supplements in cancer care from both the clinician and patient perspective. The survey was developed internally by HOPA POEC in partnership with various organizations (Cancer Care, Community Oncology Alliance, Oncology Nursing Society, and Stupid Cancer) with the goal of capturing a diverse response representation. The survey consisted of 13 questions with a mix of both fixed and open response options, asking questions to better understand current supplement usage, information sources, and current approaches to patient inquiries around OTC supplements. Survey responses were collected by HOPA members and members of partnership organization from March 3, 2026, through April 20, 2026.

Results

In total, the survey generated 344 responses, including 16 patients and 328 from healthcare providers/clinicians. Among patient respondents, most were female (84.6%). Additionally, most were ≥65 years of age (61.5%), followed by 55-65 years (23%). Cancer diagnoses were heterogenous, though predominantly solid tumors; only 2 patients with hematologic malignancies responded.  Only 13 of the 16 patients reported demographics information.

Of patients who reported supplement usage (75%), reasons included side effect management from their cancer treatment (50%), general health improvement (33.3%), and other reasons (16.7%). Some patients specified cancer prevention; however, no patients reported taking supplements as a primary cancer treatment modality. Although many patients (n=5, 41.7%) sought information directly from medical providers or a pharmacy (n=1, 8.3%), others reported finding information on healthcare-specific resources (e.g., MSKCC About Herbs – n=5, 41.6%), general internet searches (n=4, 33.3%), and social media (n=2, 16.7%). Of note, several patients reported information from more than one source. All patients reported speaking with a healthcare provider/clinician about safe supplement use during their cancer treatment and ensured their supplement was documented on their medication list. Seven patients admit being told by providers they could not continue their supplement(s) (and a reason), 2 (16.7%) reported being told to discontinue only some, and 3 (25%) were not told to stop their supplements. The most common reason for advising supplement discontinuation was a drug-supplement interaction (66.6%) or safety/side effect concern (33.3%). Patients on clinical trials additionally reported being advised against supplements while on trial. The most common supplements reported included dietary supplements (e.g., magnesium, vitamin B12, calcium/vitamin D3), and alpha lipoic acid. All except one patient reported a benefit while taking their preferred supplement.

Of the healthcare respondents, most were pharmacists (75.5%), followed by nurses, physicians, and advanced practice providers (APPs) at 13.6%, 6%, and 4.9% respectively. Healthcare counterparts reported patients report taking supplements for more than one reason, most commonly side effect prevention/management (67.8%) and general health improvement (61.8%). In contrast, healthcare providers endorsed patients taking supplements for treatment of cancer (58.5%) and prevention of cancer (24%) to be a reason for usage. Healthcare providers respondents commonly noted that their patients obtained health information from general internet searches (72.1%), social media (59%), family/friends (16.9%), artificial intelligence (AI) sources (12.1%), healthcare-specific resources (e.g., MSKCC About Herbs, 9.8%), integrative/naturopathic providers (9.5%), and pharmacists (8.2%). Commonly cited supplement resources used by healthcare provider survey respondents included MSKCC About Herbs and NatMedPro (formerly Natural Medicine Database).

While many patients might perceive their supplements as ‘natural,’ healthcare providers voiced multifactorial concerns including drug-supplement interactions, lack of regulation/contaminants, and side effects. In addition to safety concerns, providers voiced that limited clinical data and misinformation can contribute to unintentional financial toxicities when putting their faith into supplements they believe may prevent or treat their cancer.

Responses for desired resource development were heterogenous since they were obtained via open-response form, however, unifying themes included expert consensus-based guideline, evidence-based patient education materials, clinical decisions support for supplement review to standardize practice and align drug-supplement interactions data. Of the 175 open-format responses, turmeric/curcumin, vitamin C (including high-dose), vitamin D, vitamin B complex/B12, and turkey tail mushrooms were the supplements patients most inquired about to providers. Results were categorized into dietary and herbal supplements (table 1 and table 2) and listed in order of frequency reported. Though not considered an “OTC supplement,” other agents that were commonly reported were ivermectin (n=17) and fenbendazole/mebendazole (n=21).

Discussion

Findings of this survey highlight gaps in knowledge, communication strategies, and resource utilization regarding OTC supplement use in oncology care. Although most patients surveyed reported engaging in discussion with healthcare providers, patient access and reliance on the internet or social media for OTC supplement information remains a substantial concern. Interpretation is limited by the small sample size, however, given that most patient respondents were 65 years or older, it may support that these patients are more likely to look to healthcare providers as a resource compared to a younger patient population who may be more likely to seek information via social media or artificial intelligence. 

Although it is often perceived that healthcare providers discourage supplement use during cancer treatment due to limited clinical data and safety concerns, many patients reported being able to continue all or some of their preferred supplements. However, it is notable that many patients in this survey reported utilization of mostly dietary supplements which have the perception of more supporting literature and safety regulations opposed to herbal supplements that are often associated with drug-supplement interactions or hepatotoxicity. Overall, the survey highlights an unmet need for additional dialogue and shared understanding between clinicians and patients.

Based on these findings, the HOPA POEC committee plans to host a podcast episode to discuss survey results and facilitate an open forum among HOPA members and partner organizations. The goal of the podcast is to identify priority topics for a supplement-related continuing education session at HOPA 2028 Annual Conference, though presentation format remains to be determined. While being mindful of pre-existing resources, HOPA hopes to develop a clinician-patient toolkit including evidence-based education material, a supplement-decision algorithm, and guidance to identify clinically significant drug-supplement interactions or side effects (e.g., bleed risk).

OTC supplement use remains highly prevalent among patients with cancer and presents challenges in care.¹ This survey highlights the importance of proactive, evidence-based information, and conversation tools to support clinicians. Enhancing education, improving lines of communication, and optimizing trusted resources are essential to patient safety in integrating OTC supplements into the cancer treatment landscape.