NOW Calcium & Magnesium
Brand: NOW · Form: TABLET [E0155]
Our assessment
The evidence shows that calcium is essential for bone health and nerve function, but this combination supplement requires careful consideration. Our assessment is that while calcium supports bone density and neuromuscular relaxation [NIH ODS], you must be aware of potential risks and medication interactions before starting it.
How it works
Think of calcium as a key building block for your skeleton. It supports bone mineralization and density, helping keep your bones strong as you age [NIH ODS]. It also plays a role in neuromuscular relaxation, meaning it helps your muscles relax and your nerves signal properly [NIH ODS].
Safety profile
FDA received 592,059 total adverse event reports for this product category. Specific side effects can include constipation, nausea, and weight loss [NIH ODS]. At high blood levels, calcium may cause poor muscle tone, abnormal heart rhythms, and a high risk of death from heart disease [NIH ODS]. Some research also suggests high intakes might increase the risk of heart disease and prostate cancer [NIH ODS]. Calcium can reduce the absorption of several medications, including bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, and phenytoin [NIH ODS]. Data for the magnesium component is not available.
Our recommendation
Start by reviewing your current diet and any medications you take. If you use bisphosphonates, tetracycline antibiotics, fluoroquinolone antibiotics, levothyroxine, or phenytoin, take this supplement at least two hours apart from those medications [NIH ODS]. Do not exceed recommended doses, as high calcium levels in the blood and urine pose serious health risks [NIH ODS]. Consult your doctor before starting, especially if you have a history of kidney stones, heart disease, or prostate cancer [NIH ODS].
AI-assisted analysis. Data sourced from NIH DSLD.
Supplement Facts
| Brand | NOW |
|---|---|
| Serving Size | |
| Contents | 100.0 Tablet(s) |
| Market Status | Off Market |
How to Read This Label
Supplement labels contain several key sections regulated by the FDA:
- Serving Size — The recommended amount per dose. Always check this — some products require multiple capsules per serving.
- Amount Per Serving — Shows the quantity of each nutrient in the product, typically in IU (International Units), mg (milligrams), or mcg (micrograms).
- % Daily Value (%DV) — Indicates how much a nutrient in a serving contributes to a daily diet. 5% DV or less is low; 20% DV or more is high.
- Other Ingredients — Lists inactive ingredients like fillers, binders, and capsule materials (e.g., gelatin, cellulose, magnesium stearate).
- Suggested Use — The manufacturer's recommended directions for taking the supplement, including timing and dosage.
Source: FDA Dietary Supplement Labeling Guide