Oxcarbazepine is the active ingredient contained in Oxtellar XR. The 150 mg tablets contain the following inactive ingredients: colloidal silicon dioxide, hypromellose, yellow iron oxide, magnesium stearate, methacrylic acid copolymer, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, povidone, sodium lauryl sulfate, talc, and titanium dioxide. The 300 mg tablets contain the following inactive ingredients: colloidal silicon dioxide, hypromellose, yellow iron oxide, red iron oxide, black iron oxide, magnesium stearate, methacrylic acid copolymer, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, povidone, sodium lauryl sulfate, talc, and titanium dioxide. The 600 mg tablets contain the following inactive ingredients: colloidal silicon dioxide, hypromellose, red iron oxide, magnesium stearate, methacrylic acid copolymer, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, povidone, sodium lauryl sulfate, talc, and titanium dioxide. Contraindications Do not take Oxtellar XR if you are allergic to eslicarbazepine acetate, oxcarbazepine, or to any of Oxtellar XR’s other ingredients.