Vitamin D Interactions with Prescriptions and Supplements

Vitamin D

Many of us take a vitamin D or calcium supplement on the advice of our physician.  It is important to consider how the timing of taking this supplement relates to prescriptions and other supplements that you take.  Your physician should always be made aware of all supplements that you take.

Possible Prescription interactions

1. Synthroid or levothyroxine

Vitamin D or calcium supplementation can affect the absorption of some prescription medications.  It is therefore recommended to separate taking vitamin D, calcium, iron, and magnesium from your thyroid prescription medication.  This would typically be Synthroid or levothyroxine which is the most commonly prescribed medication in North America.  These products should not be taken at the same time as it can bind to levothyroxine and impair its absorption.

2. Statin or Cholesterol medications

HMG-CoA reductase inhibitors, better known as statins, are medications taken to lower cholesterol levels. Studies have shown that vitamin D supplements can lower the amount of statin medication found in your body.  Vitamin D may lower how well a statin is absorbed in your blood.  It is safe to take vitamin D and a statin medication together however your physician should be made aware that you are taking them together.  By telling your physician, he or she, can monitor your cholesterol levels closely and/or change your cholesterol medication if needed.

3. Thiazide Diuretics, Digoxin, Diltiazem

Thiazide diuretics increase calcium levels in the blood by lowering the amount of calcium lost through urine. Taking thiazides with vitamin D can also cause higher calcium levels (hypercalcemia).

High calcium levels can increase your risk for abnormal heart rhythms (arrhythmias) if you also take digoxin.

Vitamin D can increase your risk for hypercalcemia. High calcium levels can increase your risk for arrhythmias if you are also taking diltiazem.

Your physician should always be aware and know if you are taking any of these medications or others with Vitamin D.  Symptoms of hypercalcemia (or high levels of calcium) include nausea, vomiting, increased thirst, frequent urination, muscle weakness, bone pain, and confusion.  If you take medications for arrhythmias or other heart conditions, monitor for any signs or symptoms of worsening arrhythmias. Symptoms include fast or slow heart rate, feeling like your heart is skipping a beat, dizziness, lightheadedness, shortness of breath, chest pain, or sweating.  You should seek immediate medical attention if you are experiencing any of these symptoms.

Always keep your Physician aware of all supplements you take especially with Prescription medications.