The most common side effects of psyllium seed are gas, cramping, diarrhea and nausea, according to WebMD. Some people experience allergic reactions to psyllium that may require medical attention.
The most common reaction to psyllium seed is gastrointestinal discomfort. Psyllium seed requires drinking 8 ounces of water with every 7 grams of seed to prevent the product swelling in the throat, states WebMD. This swelling causes choking, chest pain and vomiting. Allergic reactions occur in some individuals and involve sneezing, swollen eyelids and nasal passages, hives, and asthma. Repeated and prolonged exposure to psyllium increases the risk of allergic reaction. If these reactions progress to flushing, tightness of the chest or throat, facial swelling, difficulty breathing, or fainting, immediate medical attention is necessary.
Patients with Type 2 diabetes should be aware that psyllium can lower blood sugar, reports WebMD. Psyllium also lowers blood pressure, presenting a concern to those with already low blood pressure. There is evidence that psyllium seed increases the risk adenoma in individuals with previous colorectal adenomas and that it exacerbates gastrointestinal disorders, such as constipation. Doctors recommend stopping ingestion of psyllium at least two weeks prior to surgery due to the product's effects on blood sugar.