Why Do I Feel Worse After My B12 Injection? PA Relief Serious Side Effects of Vitamin B12? We often overlook the subtle signs that our body is signaling for help. Low vitamin B12 levels can lead to symptoms like brain fog, weakness, and even numbness in your limbs. These Medications That Can Cause Hypokalemia Low potassium isn't always from diet some meds can trigger it! Diuretics Corticosteroids Beta agonists Insulin Stay aware, stay safe!