Niacin is a natural vitamin B3 treatment that may help prevent or treat high cholesterol, Alzheimer's disease, diabetes, cancer or other specific medical problems, MayoClinic.com health professionals report. This supplement is typically administered orally or by injection and its safety and effectiveness have not been approved by the U.S. Food and Drug Administration. Rarely, people taking niacin for the first time can experience a severe allergic reaction. People who develop anaphylactic shock symptoms from niacin require immediate medical attention.
Breathing or Swallowing Difficulties
An allergic reaction to niacin, also called anaphylaxis or anaphylactic shock, can cause breathing difficulties in certain people. Affected people can develop a cough, shortness of breath or wheezing. These symptoms arise because a person's airway abnormally constricts following an allergic response to niacin. Certain people can also develop difficulty swallowing or nasal congestion, MedlinePlus health professionals report. Without prompt treatment, these anaphylactic shock symptoms from niacin can become progressively worse and may cause certain people to stop breathing.
Heart Rate Changes
Unusual heart rate changes can occur during an anaphylactic response to niacin. Affected people can develop an unusually fast or slow heart rate due to a dramatic drop in their blood pressure, UpToDate explains.
Upset Stomach
After taking a dose of niacin, certain people can develop upset stomach symptoms due to an allergic reaction to this supplement. Upset stomach symptoms of anaphylactic shock can include nausea, vomiting, diarrhea and abdominal cramping, MedlinePlus warns.
Hives or Skin Swelling
Red, irritated and inflamed welts called hives can appear across a person's skin due to allergy to niacin. These hives can itch profusely and can develop on any region of the body. Certain people can also experience unusual swelling of the lips, mouth, tongue or throat following treatment with niacin, Drugs.com medical professionals explain. Oral swelling can contribute to swallowing and breathing difficulties in allergic people.
Dizziness or Fainting
Low blood pressure due to a severe niacin allergy can cause dizziness or lightheadedness in affected people, MedlinePlus reports. In certain cases, allergic people exposed to niacin can faint, collapse or lose consciousness.
Confusion or Anxiety
Anaphylactic shock following niacin treatment can cause affected people to appear unusually confused or anxious, UpToDate medical professionals report. These symptoms typically occur in conjunction with other anaphylaxis symptoms, such as breathing difficulties or heart rate irregularities.
