The sting of a jellyfish comes from specialized cells in the surface of its tentacles, known as cnidocytes. Each small, bulb-shaped cell holds a nematocyst, a barbed, threadlike tube that is ...

Some causes of a swollen penis include balanitis, contact dermatitis, urethritis, and priapism. Treatment may include home remedies, topical ointments, medications, and surgery. Penile swelling is ...

Less commonly, testosterone injections can cause prolonged erections, nausea or vomiting, difficulty urinating, swelling of the hands and feet, and difficulty breathing (especially during sleep).