Linda Elsegood discovered LDN after relapsing/remitting MS, which caused her to have attacks every six months. It took months for a relapse to recede, only to have another begin. In October 2003, Linda was advised she had secondary progressive MS and there was nothing anyone could do to help her, and like so many people sought alternative options for her own healthcare. Following her success with LDN, Linda Elsegood founded the LDN Research Trust as a UK nonprofit registered charity in 2004. The LDN Research Trust ( is run by volunteers; they receive no funding and rely on donations. The team liaises closely with prescribers, pharmacists, and patients, offering support and education.

Author Linda Elsegood

Author Linda Elsegood

Low Dose Naltrexone (LDN) holds the potential to help millions of people suffering from various autoimmune diseases and cancers. It has been used to help those with autism, chronic fatigue, and depression find relief, and latest research points to its potential for long covid, mold toxicity, even longevity. Administered off-label in small daily doses (0.5 to 4.5 mg), this generic drug is extremely affordable and presents few known side effects. So why has it languished in relative medical obscurity? Find out more about the potential of LDN from leading international medical professionals in this updated, third book, edited by Linda Elsegood, founder of The LDN Research Trust.


Could you introduce The LDN Book 3 to new readers?

The LDN Book 3, is the 3rd book in our series, and it is a stand-alone book, it explains the History, Pharmacology, and Mechanism of action of Naltrexone, and dosing protocols and is a must for people battling Long Covid, Mold and CIRS, Depression, Mixed Connective Tissue Disease, Ophthalmic Conditions, Cancer and using LDN for Longevity.

What is LDN?

LDN is a pure inhibitor, so there is no narcotic effect. The chemical structure is almost identical to endorphins that we make naturally called met-enkephalin, also known as OGF or Opioid Growth Factor.

LDN is an antagonist at the OGF receptors and there are OGF receptors on a wide range of cells in the body.  When we talk about low dose naltrexone we mean doses that are a 10th or less of the standard dose of Naltrexone. Most of the research studies have used 4.5mg per day. Doses range from 0.001mg – 16mg in clinical practice.

Low Dose Naltrexone binds to the endorphin receptors for about 1 – 1/2 hours, and the blockade lasts about 4 - 6 hours. The effects of LDN are analgesia and anti-inflammatory.  One of the other effects is that it increases the production of your own endorphins.

-        Naltrexone exists in a racemic mixture of isomers ("left-handedness and right-handedness")

-        Dextro-naltrexone binds toll-like receptors (TLR)

-        Levo-naltrexone binds opioid receptors


-        Antagonist effect at Toll-like receptors (TLR)

-        TLR-4 receptors exist on microglial cells, other macrophages, mast cells

-        Activated microglial cells produce proinflammatory cytokines, substance P, nitric oxide

-        Inhibition leads to a decreased proinflammatory cascade


-        Antagonist effect at opioid receptors

-        Small temporary opioid blockade

-        Upregulates endogenous opioid production

-        Upregulates opioid receptors

-        Increased endorphins favourable to the immune system

Endorphins are your natural peptides produced in many cells which regulate cell growth, including your immune cells. Many patients who have autoimmune disease tend to have low levels of endorphins, Met-enkephalin, aka opioid growth factor (OGF), an important immunomodulatory. Opioid receptors are in the central and the peripheral nervous system, the GI tract, and on lymphocytes. By using LDN you receive a brief blockade, creating a rebound effect giving you more endorphins, including OGF, and increased production of the OGF receptors.

When did you first hear about LDN?


How does LDN work?

Understanding how LDN works requires a grasp of three fundamental biological principles.

First, opiate receptors are present in multiple biological systems in the human body, as they regulate a great number of biological functions via the central release of natural opiates (endorphins/met-enkephalins). (1) (2)

Second, a class of proteins called toll-like receptors (TLRs) are part of the immune system, providing a first line of defence against microbial invasion and possessing the ability to recognize and be activated by not only pathogens but also endogenous signalling molecules. (3)

Lastly, naltrexone, when given at a low dose, has antagonistic activity in both of these areas, and is able to modify biological functions of these receptor groups by suppressing unwanted immune reactions, or by stimulating disease-suppressed immune activity. (4)

Naltrexone, taken at the full dose of 200mg daily, has been licensed for use for the treatment of addictions since 1984. (5) It is currently used for both opiate and alcohol addiction, as a full dose is able to completely block endogenous (endorphins released by the brain) and exogenous (recreational drugs such as heroin) opiates. In the licensed dose, it is used as an oral tablet, a long-acting injection, and as an additive in painkillers to prevent them from being abused. (5)

As have many drugs that have been widely used for an extended period, naltrexone has been found to have different actions when used in lower doses than originally intended. These in part are due to the chiral nature of the molecule and the different, dose-dependent effects of the Levo and Dextro isomers of naltrexone.

The concept of chirality is not new, (chiral chemistry was discovered by Louis Pasteur in 1848), like all drugs when synthesized are produced as a racemic mixture of 50:50 left- and right-handed molecules. (6)  Half of the mixture synthesized is a left-handed shape and the other half is a right-handed shape. Although consisting of the same components, and being chemically identical, they have different shapes (as with left and right hands), enabling the different isomers to interact with different groups of receptors in the body.

In general, most drugs only have biological activity in the human body in Levo (left) handed shape, as this is how most of the receptor groups in the human body are arranged. Common examples of these drugs—such as levothyroxine, levocetirizine, levobutanol—are manufactured as racemic mixtures of 50:50 Levo and Dextro isomers; however, the manufacturer discards the Dextro isomer and presents the medication in the Levo-only form, sometimes because the Dextro isomer carries unwanted side effects, or is not active on the intended target receptor. (7)

In the case of naltrexone, the Levo isomer interacts with the commonly understood opiate (endorphin) receptors group and the Dextro isomer interacts with the toll-like receptor group. (8) (9)

The basic effects of LDN can be summarized as follows:


-        Blocks (antagonises) some TLR receptors

-        Reduces production of pro-inflammatory cytokines

-        Suppresses cascade inflammation

-        Central and system effects as TLR receptors are present on microglial cells, mast cells, and macrophages


-        Blocks opiate receptors for a brief period

-        Increases natural production of anti-inflammatory endorphins

-        Upregulates opiate receptors

-        Has direct effect on some cell proliferation rates

What diseases and illnesses can it treat, and how successfully? 

Autoimmune diseases, MS, Crohn’s Disease, Rheumatoid Arthritis, Chronic Pain, EDS, Fibromyalgia, Mental Health, Women’s Health, Paediatric Conditions, Cancer, Long Covid, ME and more. It is reported by our Medical Advisors when starting low and titrating slow they are seeing 80+ % of success. 

What inspired you to publish the book?

It was to follow on to the first 2 books, it covers new conditions not in the first 2 books.

The LDN Book 3 is an updated version, what is there that is new in this edition? 

Long Covid, Mold and CIRS, Depression, Mixed Connective Tissue Disease, Ophthalmic Conditions, Cancer and using LDN for Longevity.

You were diagnosed with relapsing / remitting MS in 2000; what has LDN done for you?

LDN has giving me my life back, I still know I have MS, but I can achieve things and participate in life.

What is the LDN Research Trust?

The LDN Research Trust is a registered charity no 1106636 set up in 2004

Why did you register it as a charity?

I was told it was the only way to be taken seriously.

What message are you trying to get out to medical professionals and patients?

I’m trying to share accurate, scientific information regarding LDN for the hundreds of conditions LDN could potentially help with. Once an LDN prescriber understands LDN and sees the results with the first patient, they prescribe it for. They are fully onboard and offer it to other patients where it could be of benefit.

Why doesn’t everyone know about LDN?

Naltrexone is an out of patent drug, which means there is no big pharma behind it or promoting it. Even though Naltrexone has been fully trailed back in the late 1970s, LDN still awaits large-scale double-blind placebo trials. Many small trials have been carried out check PubMed. 

What is the aim of The LDN Book 3?

To further raise awareness of LDN and for the condition included in the book. 

Can any doctor prescribe LDN?

Any prescriber can prescribe LDN and on the NHS if they so choose. It is an orphan drug, prescribed off label on a named patient basis.

Could you tell us more about the conference in June?

The LDN conference in June is a 3-day live event that is also live streamed around the world. The aim is to bring the latest research, and experience for a multitude of conditions, and the highlight for the medical professionals if the 5 hours of Q&As where people can submit their questions online in real time and have the expert panel answer them. 

What has the response to the book been like so far?

The feedback for book 3 has been incredible, we are very pleased and hope it helps not just medical professionals but patients what a deep insight to the conditions covered.

What do you hope that readers take away from the book?

Accurate, scientific information which they can use to better their or their patients’ health.

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