Vitamin D 5000 µg (200,000 IU) Should Be Taken Weekly, Not Daily
A 5000 µg (200,000 IU) dose of vitamin D3 should be taken weekly for 8–12 weeks as a loading regimen to correct deficiency, never daily, as daily administration of this dose would result in severe toxicity. 1
Critical Dosing Clarification
You are asking about 5000 µg, which equals 200,000 IU (since 1 µg = 40 IU). This is an extremely high dose that requires careful context:
If You Meant 5000 IU (125 µg):
- Take daily as a maintenance or treatment dose for patients with obesity, malabsorption, or chronic deficiency 2
- This dose (7000 IU daily or less) is safe for prolonged use in high-risk populations 2
- Daily doses up to 4000 IU are considered completely safe by most authorities, with evidence supporting up to 10,000 IU daily for several months 1, 3
If You Actually Meant 200,000 IU (5000 µg):
- Never take daily – this would cause severe hypervitaminosis D and hypercalcemia within weeks 4
- A case report documents that 50,000 IU daily (¼ of your stated dose) caused hypercalcemia, acute kidney injury, confusion, and slurred speech within 3 months 4
- Toxicity typically occurs with daily intake exceeding 100,000 IU or serum 25(OH)D levels above 100 ng/mL 1, 3
Standard Evidence-Based Regimens
For Vitamin D Deficiency (<20 ng/mL):
- 50,000 IU weekly for 8–12 weeks is the gold-standard loading regimen 1
- This can use either ergocalciferol (D2) or cholecalciferol (D3), though D3 is preferred 1
- After loading, transition to maintenance: 800–2000 IU daily or 50,000 IU monthly 1
For High-Risk Populations Requiring Higher Doses:
- 7000 IU daily is safe for prolonged prophylaxis in obese patients, those with liver disease, or malabsorption 2
- 30,000 IU weekly (or twice weekly for treatment) is an alternative intermittent regimen 2
- 50,000 IU weekly for 6–8 weeks only for treatment of deficiency in high-risk groups 2
Why Weekly Dosing Works for High Doses
- Vitamin D has a long half-life, allowing weekly administration to maintain steady serum levels 1
- Weekly 50,000 IU dosing reliably raises 25(OH)D by 40–70 nmol/L (16–28 ng/mL) over 8–12 weeks 1
- Daily dosing is physiologically preferred for maintenance, but weekly dosing improves compliance for loading phases 3
Critical Safety Thresholds
- Upper safe daily limit: 4000 IU for general population 1, 5, 6
- Extended safety: up to 10,000 IU daily for several months in specific circumstances 1, 3
- Toxicity threshold: >100,000 IU daily or serum levels >100 ng/mL 1, 3
- Hypercalcemia risk increases significantly with daily doses of 3200–4000 IU (RR 2.21), though absolute risk remains low at 4 cases per 1000 individuals 6
Monitoring Requirements
- Recheck 25(OH)D levels 3 months after starting any supplementation regimen to assess response 1, 3
- Monitor serum calcium every 3 months during high-dose therapy 1
- Discontinue immediately if serum calcium exceeds 10.2 mg/dL (2.54 mmol/L) 1
- Target serum 25(OH)D of 30–44 ng/mL for optimal health benefits 1, 7
Common Pitfalls to Avoid
- Never use single annual mega-doses (≥300,000 IU), as they paradoxically increase fall and fracture risk 1, 3
- Do not confuse IU with µg: 1 µg = 40 IU, so 5000 µg = 200,000 IU (a potentially lethal daily dose)
- Avoid intermittent doses >50,000 IU weekly for routine supplementation, as larger bolus doses may be inefficient or harmful 5
- Ensure adequate calcium intake (1000–1200 mg daily) during vitamin D treatment 1
- Weekly doses of 50,000 IU (1250 µg) increase hypercalciuria risk, particularly in individuals with BMI >26 kg/m² 8