Widely used as a sedating antihistamine, it is commonly found in over-the-counter sleep aids due to its ability to promote drowsiness. It is also a key ingredient in medications for relieving short-term insomnia. Often combined with pain relievers or other drugs, it helps manage nighttime cold and allergy symptoms. In some formulations, it is used to reduce nausea and vomiting during pregnancy, typically in combination with vitamin B6. Due to its central nervous system depressant effects, it may cause drowsiness and is usually taken at bedtime.