Purity: Medical-grade supplements are made to stricter standards, ensuring fewer fillers, binders, and contaminants. Over-the-counter supplements may not always be as rigorously tested for purity.

Sourcing and Potency: These supplements often contain more bioavailable forms of nutrients (the form your body can more easily absorb) and in the correct dosages needed for therapeutic effects.

Medical-grade supplements are often formulated to target specific health issues, with precise dosages that a doctor may adjust based on your needs. OTC supplements might not be as tailored to individual health needs and can vary in quality or potency from batch to batch.

No One-Size-Fits-All: Because these supplements are prescribed or recommended by professionals, they are often part of a comprehensive treatment plan, ensuring that you're getting the right amount of nutrients to address a specific deficiency or condition.

The formulation of medical-grade supplements often takes bioavailability into account, ensuring that the nutrients are in a form your body can absorb efficiently. OTC products may use cheaper, less effective forms of vitamins and minerals, which might not be as well absorbed.

Medical-grade supplements are often produced by companies that are subject to more stringent regulations, either by health professionals or governing bodies. While OTC supplements are regulated by the FDA, they don’t require the same level of oversight or clinical testing as prescription-grade products.

Because medical-grade supplements are typically prescribed or recommended by healthcare providers, they come with the benefit of professional oversight. Your doctor or nutritionist can monitor your progress and adjust dosages as needed, ensuring that you're on the right track.

Medical-grade supplements are often backed by clinical studies, so you have a better idea of their efficacy and safety. This is in contrast to OTC products, which might lack clinical validation or have limited evidence supporting their claims.

In cases where specific deficiencies are affecting your health, medical-grade supplements might be the most effective route to address those issues. For example, a medical-grade vitamin D supplement could help someone with severe deficiency, where a basic OTC one might not be sufficient.

OTC supplements can sometimes include unnecessary fillers, artificial colors, or preservatives. Medical-grade supplements generally focus on purity and are less likely to contain ingredients that aren't directly beneficial for your health.