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Jump to Key Points A high-dose vitamin D supplement for adults instead of the usual treatment to prevent rickets: The German Federal Institute for Risk Assessment (BfR) has once again reported a case of severe vitamin D intoxication in an infant. The case illustrates how quickly highly concentrated supplements in particular can become dangerous — and which symptoms should raise suspicion of hypervitaminosis D in clinical practice.
High-Dose Adult Supplement Led to Intoxication
Vitamin D is part of established preventive care for infants. However, supplementation itself can pose a health risk if unsuitable or highly concentrated supplements are used. In July 2026, the BfR was again notified of a severe case of vitamin D poisoning in an infant. According to the institute, the cause was the incorrect administration of a high-dose dietary supplement intended for adults, which the parents had purchased online. A similar case had already been reported to the BfR at the end of 2021.
These case reports are also relevant because vitamin D supplementation in infancy is standard medical practice. Infants cannot adequately meet their needs through cutaneous synthesis; at the same time, breast milk provides only relatively small amounts of vitamin D. In Germany, a daily supplement of 400-500 IU or 10.0-12.5 µg of vitamin D is therefore recommended for infants, depending on their birth date until their second spring/early summer.
The Real Problem Is the Dose
Physiologically, vitamin D plays a central role in calcium and phosphate metabolism and thus in the mineralization of growing bone. However, excessive intake can reverse this effect into a pathological state: In cases of hypervitaminosis D, intestinal calcium absorption increases, which can lead to the development of pronounced hypercalcemia.
- Infant vitamin D prophylaxis standard; usual dose 400-500 IU/day.
- Adult high-dose vitamin D supplement caused severe infant intoxication.
- Hypervitaminosis D → hypercalcemia; symptoms often nonspecific initially.
- Key symptoms: poor feeding, vomiting, drowsiness, constipation, FTT, polyuria.
- Persistent hypercalcemia may cause nephrolithiasis, nephrocalcinosis, renal impairment.
In infants in particular, intoxication may initially present with nonspecific symptoms. Reported symptoms include, among others, poor feeding, vomiting, drowsiness, muscle weakness, constipation, weight loss, and failure to thrive. Polyuria, dehydration, and electrolyte imbalances may also occur. As a result, the clinical picture can initially be easily misattributed to other pediatric conditions.
Persistent hypercalcemia poses a particular risk for renal complications. These can range from nephrolithiasis and nephrocalcinosis to potentially irreversible impairment of kidney function.
Highly Concentrated Drops Pose a Particular Risk for Error
From the BfR’s perspective, a major risk factor lies in preparations whose dosage is not tailored to infants. Particularly problematic are high-dose dietary supplements intended for adults, as well as products designed for weekly or monthly use. If such an amount of active ingredient is accidentally administered daily, the cumulative dose can rapidly multiply.
Highly concentrated liquid preparations deserve special attention. With drops, it is not only the volume administered but also the specific concentration of the active ingredient that determines the actual vitamin D dose delivered. Preparations from different manufacturers are therefore not readily interchangeable.
For clinical practice, this raises a simple but important point: During the medical history, healthcare providers should not only ask whether parents are giving vitamin D, but also which specific supplement, at what concentration, and how often it is administered. In cases of unclear symptoms and a corresponding history of supplementation, vitamin D intoxication, or hypercalcemia should be considered in the differential diagnosis.
The Key Is Choosing the Right Supplement
The warning against overdoses does not explicitly call into question established vitamin D prophylaxis. For infants, 400-500 IU or 10.0-12.5 µg of vitamin D per day is still recommended; in Germany, supplementation typically continues through the first 12-18 months of life or until the child’s second early summer.
Rather, it is crucial to advise parents on a clear, infant-appropriate dosage when prescribing and providing counseling. Especially when purchasing dietary supplements online, it is worth inquiring about the product, concentration, and dosing schedule.
This story was translated from Medscape's German edition. .
