Doxylamine is a pharmaceutical compound used to treat short-term insomnia and is an ingredient in many allergy and cold medications. It is an antihistamine, which means that it blocks the body’s histamine receptors. Histamine receptors cause the sneezing, runny nose, and itchy eyes often associated with allergies and colds. A full dose of doxylamine causes severe drowsiness in most people, and as such, it is usually only taken as a sleep aid. In allergy and other medications, the drug is typically blended with other medications.
Most doxylamine designed for insomnia treatment comes in pure or near-pure dosages. These dosages commonly come as a gelcap pill, a chewable tablet, or liquid. Once ingested, the drug begins systematically blocking histamine receptors, and acts as a sedating antihistamine because of how powerfully it disrupts the histamine process. It is classed as a short-term sedative, but sleepiness can persist for seven hours or more. Patients are usually advised against taking the drug if they do not have enough time for a thorough rest.
When used for cold or allergy relief, the drug is typically added in small doses so as not to cause intense sleepiness in patients who need to remain alert. Doxylamine is a highly effective antihistamine, but it is not the only antihistamine available. It is often combined in allergy medication with other antihistamines, as well as cough suppressants, fever reducers, and the like.
Doxylamine is a drug, but it is not usually marketed as a medication under that name. Even medications that are made up entirely of doxylamine are sold under pharmaceutical company brand names. The ingredient list on the back of the box or bottle will identify whether or not a medicine contains the compound, but the medicine’s name rarely will.
Whether doxylamine or doxylamine-containing medications are available over the counter is mostly a matter of local law. Some countries allow most drugs to be sold without a prescription, either freely on shelves or dispensed by a pharmacist. Other countries have tighter drug regulations, and exert more control over not only how drugs can be sold, but also over which drugs can be sold and where. Doxylamine is generally considered to be a low-risk medication, but its availability may be different in different places.
Unless otherwise directed by a doctor, doxylamine and the drugs that contain it are not meant to treat long-term conditions, and are not always safe for use over extended periods of time. As an insomnia drug, it is usually only safe to use for a fixed period. Sleep disorders and persistent insomnia may not be cured by the drug. Similarly, it should not be taken for longer than about a week as a cold and allergy medication. Colds and allergies that persist for many days should generally be brought to the attention of a medical professional.