Senna generally takes about 6 to 12 hours to work when taken orally in tablet or tea form. It is best taken at bedtime so that it works overnight. Liquid forms of senna may work a bit faster, often within 1 to 3 hours. The timing can vary depending on individual digestive factors and the form of senna used. If no effect is seen after 12 hours, it is usually advised not to take another dose and to consult a healthcare professional. Common side effects include stomach cramps and diarrhea, and senna is recommended for short-term use only, typically not more than a week.
