How significant is the risk of drinking when taking isoniazid?

Fairly significant! Age appeares to be the predominant factor influencing the risk of developing isoniazid-related hepatitis (increasing age is associated with an increasing risk). Drinking alcohol, especially on a daily basis, enhances the risk of hepatitis among those taking isoniazid.Weighing the benefits of Isoniazid in preventing tuberculosis against the risk of its causing hepatitis nec. F/u with your doctor.