LDn

Ldn is an abbreviation with multiple meanings, depending on context. The two most common are informal shorthand for London and the medical acronym for low-dose naltrexone. In everyday use, Ldn or LDN is often seen in social media, messaging, or casual writing as a compact reference to the city, though it is not an official designation and formal references typically spell out London or use standard codes such as LON in travel or postal contexts.

In medical and patient contexts, LDN refers to low-dose naltrexone, a pharmacological approach used off-label for various autoimmune, inflammatory, and pain-related conditions. Doses are typically much lower than those used for treating addiction, commonly around 1 to 4.5 milligrams per day. The proposed mechanism involves a brief blockade of opioid receptors, which is theorized to lead to an upregulation of endogenous endorphins and enkephalins and to modulate immune or microglial activity; however, the exact mechanism is not fully established and evidence for broad clinical benefit remains mixed. Regulatory status varies by country, with naltrexone itself approved at higher doses for addiction treatment and low-dose use occurring off-label in many regions.

Clinical guidance emphasizes consulting healthcare professionals before starting LDN, as effectiveness can vary and long-term safety data are limited for some conditions. Side effects are generally mild but can include sleep disturbances, vivid dreams, headaches, or gastrointestinal symptoms. LDN remains a topic of ongoing research and discussion within medical communities and patient groups.