Over-the-counter sedatives are drugs that help a person get some sleep. However, it is not advisable to take them regularly as they contain antihistamines and, as tolerance to these increases, they may not make a person sleepy. Some of them can leave a person feeling unwell, as stated by Mayo Clinic
The most common over-the-counter sedatives that many people use include diphenhydramine, valerian, melatonin and doxylamine succinate. The examples of diphenhydramine include Unisom SleepGels and Benadryl, among others, and are all sedating antihistamines. These drugs have different side effects, including urinary retention, dry mouth, constipation and blurred vision. These side effects apply to doxylamine, which is also a sedating antihistamine.
Melatonin is a hormonal supplement that helps to reduce the time a person takes to get to sleep. It has mild side effects, such as daytime sleepiness and headache. Valerian is a plant that is used to make different supplements that help aid sleep. They are known not to cause any side effects.
Before taking any drug, it is important to seek medical advice first. A person needs to inform the doctor if he or she is suffering from any condition that may get worse should they use sedatives. Avoiding alcohol while using sedatives is also an important factor to keep in mind, as stated by Mayo Clinic.