NHS experts warn vitamin D users about four key overdose symptoms

Why this warning matters

NHS experts warn vitamin D users about four key overdose symptoms at a time when many adults rely on supplements. With around 42% of UK adults taking vitamin D supplements, clear guidance on safe use is important. The NHS recommends vitamin D in winter, but healthcare professionals say excessive intake can cause troubling and sometimes hard-to-spot symptoms.

Main signs to watch for

Four key overdose symptoms

Experts highlight four red-flag symptoms that may indicate too much vitamin D: persistent thirst, frequent urination, nausea and aches or cramps. These signs can be subtle and overlap with other conditions, so users should be alert to changes after starting or increasing a supplement.

Other associated symptoms

Clinicians have also reported that excess vitamin D can cause headaches, episodes of brain fog and further digestive symptoms such as vomiting. Early signs like nausea and headache are particularly tricky because they resemble common ailments and may delay recognition of an overdose.

Context and guidance

The NHS continues to advise taking vitamin D during the darker months for people at risk of low levels. However, experts emphasise that more is not always better. Overconsumption — often from high-dose supplements or combining products — raises the risk of adverse effects. Users are advised to check product labels, follow recommended dosages, and avoid combining multiple supplements unless advised by a healthcare professional.

News outlets reporting on the issue noted the update on 21 January 2026, underlining current concern among clinicians and public-health commentators about supplement safety in the general population.

Conclusion: what readers should do

Readers who take vitamin D should monitor for the four key overdose symptoms — increased thirst, frequent urination, nausea and aches or cramps — and be aware of related signs such as headaches or brain fog. If these symptoms appear, stop the supplement and seek medical advice. For most people, following NHS dosing advice and checking combined supplement use will reduce risk. As supplement use remains widespread, the warning is a timely reminder to use vitamin D thoughtfully and under guidance when in doubt.