There are generally few or no side effects of vitamin D as long as the amount ingested is within the recommended limits. Overdosing on vitamin D can have negative side effects such as kidney problems. Conversely, not getting enough of it can lead to bone diseases from a deficiency. Additionally, some prescription drugs can interact with vitamin D and cause side effects.
The recommended dosage to avoid the side effects of vitamin D can vary, but there are some generally agreed upon amounts. Children and adults under 50 years old should get between 200 and 400 international units (IU) per day. Those aged 51 to 70 should strive for 400 IU daily, and those over 70 years old should get around 600 to 1,000 IU. More than 1,000 IU per day can be toxic for children, and over 2,000 IU can be toxic for adults. The toxic levels can lead to an overdose and negative side effects of vitamin D.
An overdose of vitamin D can cause problems with the heart, bones, and kidneys. Symptoms include loss of appetite, vomiting, constipation, and weakness. Further side effects of vitamin D in large amounts are hypercalcemia and excess bone loss. The symptoms of hypercalcemia can be nausea and vomiting, frequent urination, excess thirst, and fatigue. Also, toxic levels of vitamin D can impair kidney functions, leading to kidney stones and calcium deposits throughout the body.
On the other hand, a deficiency can lead to adverse side effects of vitamin D. One major consequence of a vitamin D deficiency is that it can cause rickets, which is a bone disease characterized by bone tissue that does not mineralize properly. It can also result in soft bones and skeletal deformities. The symptoms of a deficiency include bone pain and muscle weakness. It might be necessary for one to take a vitamin supplement to prevent side effects from a deficiency.
Additionally, many medications can cause interactions and side effects of vitamin D, such as affecting calcium absorption and the rate that vitamin D is metabolized by the body. Medications that can interact with the vitamin include steroids, seizure drugs, and some weight loss drugs. Also, medications that are used to treat high blood pressure and heart problems can increase the risk of side effects of vitamin D. If one is taking medication, it might be necessary to consult a doctor before taking a vitamin D supplement to see if there are any interactions that could produce negative side effects.