Fibercon and Benadryl may be administered together without a risk of known drug interactions. However, any fiber supplement, such as Fibercon, can reduce the absorption of medication due to how it binds water in the GI tract. Therefore, it is generally recommended to take medication at least 60 minutes before fiber or 2 hours after fiber. Taking any medication with fiber can reduce its effectiveness.

Benadryl Information

Benadryl belongs to a group of medications known as antihistamines. The active ingredient in Benadryl is diphenhydramine. Diphenhydramine prevents binding of histamine to histamine (H1) receptors by competing with histamine for binding sites. By displacing histamine,this allows for the relief of symptoms commonly seen in an allergic reaction such as redness, irritation, itching and nasal congestion.

Additionally, diphenhydramine can cause significant sedation in individuals and for this reason is often used as a sleep aid.


Fibercon has the active ingredient calcium polycarbophil. It is classified as a bulk forming laxative and is primarily used to alleviate symptoms of chronic constipation and irritable bowel syndrome. In addition, it can be used as a treatment of diarrhea.

Fibercon works by binding water and functioning as a hydrosorptive agent. As an anti-diarrheal medication, FIbercon works by absorbing free fecal water leading to the formation of a gel to aid in the production of solid stools. To alleviate constipation, it retains water in the intestines which increases peristalsis allowing for faster relief of bowel movements. Fibercon is a hydrophilic resin that is not absorbed by the body.

Taking Fibercon will add a significant amount of calcium to your diet. Each dose (625 mg) contains approximately 125 mg of calcium and therefore must be used cautiously in those with high calcium levels.