After taking a bath, the patient appears to have red eyes, usually due to conjunctivitis, allergy or physiological factors. 1. Conjunctivitis: when a patient with conjunctivitis takes a bath, if the hot water splashes inside the eyes, the hot water may aggravate the inflammation, so the patient may have conjunctival congestion, and therefore may show redness of the eyes. 2. Eye allergy: if the patient is allergic to shampoo, face wash and other liquids, it may stimulate the conjunctival tissue to trigger an allergic reaction, which may lead to the patient’s conjunctival congestion, resulting in the patient’s eyes red. 3. Physiological factors: when patients take a bath, if the water is particularly hot, it may be due to the increase in eye temperature, which induces vasodilatation of the conjunctival tissues, which is physiological congestion, and the patient may experience redness of the eyes. It is recommended that patients with obvious redness of the eyes should consult the hospital in time to assess their condition and follow the doctor’s instructions for treatment.