# Nicotine salt

Nicotine salts are salts formed from nicotine and an acid. They are found naturally in tobacco leaves. Various acids can be used, leading to different conjugate bases paired with the ammonium form of nicotine.

## Research

Research on nicotine salts is limited. Possible health risks of persistent inhalation of high levels of nicotine salts are not fully known. "Juul products use nicotine salts, which can lead to much more available nicotine," Principal Deputy Director Dr. Anne Schuchat of the Centers for Disease Control and Prevention (CDC) stated in September 2019. She also stated that the nicotine salts "cross the blood brain barrier and lead to potentially more effect on the developing brain in adolescents."
Recent research has further highlighted potential health risks associated with nicotine salts. A 2024 study from the University of Louisville raised concerns about the cardiovascular effects of nicotine salts, particularly when used in pod-based devices like Juul. The study found that higher concentrations of nicotine salts may increase the risk of cardiac arrhythmias.
Additionally, a 2022 study from the University of North Carolina found that users of nicotine salt e-cigarettes exhibited immune suppression markers not seen in users of other types of e-cigarettes. This study focused on "fourth-generation" e-cigarette devices and identified biomarkers indicative of airway injury and immune system suppression. However, the long-term health implications of these immune system changes remain unclear, and further studies are required.

## Types

A nicotine base and a weak acid such as benzoic acid or levulinic acid is used to form a nicotine salt. Across a sample of 23 nicotine salts available for public purchase, the three most common acids used in the formation of nicotine salts were lactic acid, benzoic acid and levulinic acid. Benzoic acid is the most used acid to create a nicotine salt. Nicotine pyruvate is another form of nicotine salt. A chemical reaction with a pyruvic acid is used to aerosolize nicotine.

## Level and rate of delivery

A free-base nicotine solution with an acid reduces the pH, which makes it possible to provide higher levels of nicotine without irritating the throat. Nicotine salts are thought to amplify the level and rate of nicotine delivery to the user. The speed of nicotine salts uptake into the body with the use of electronic cigarettes is close to the speed of nicotine uptake from traditional cigarettes. Traditional cigarettes provide high levels of nicotine, but with the taste of tobacco and paper smoke which many may find undesirable. Pod mods, however, can provide high levels of nicotine without the negative smoking experience.
Nicotine salts are less harsh and less bitter and as a consequence e-liquids that contain nicotine salts are more tolerable even with high nicotine concentrations. Nicotine salts in aerosol form do not generally generate the sensation of irritation in the chest and lungs that regular cigarettes do. Protonated nicotine salt is easier for less experienced users to inhale. This smoother experience of nicotine delivery into the body makes nicotine salts popular amongst those new to vaping e-liquids and those seeking a nicotine replacement therapy that is more commensurate to smoking traditional cigarettes.
As of 2023, many manufacturers in the United Kingdom have been observed to have shifted to nicotine salt-only disposable pods, after previously offering a majority of products in conventional liquids containing freebase nicotine. This is widely seen as being due to nicotine salt's more addictive nature.

## Brands

The latest generation of e-cigarettes, "pod products," such as Juul, have the highest nicotine content (50 mg/mL), in protonated salt, rather than the free-base nicotine form found in earlier generations. In June 2015, Juul introduced a pod mod device containing nicotine salt. British American Tobacco stated that they have been using nicotine salts in their US Vuse e-liquid brand since 2012.
There has been a proliferation of pod-based products with high nicotine concentration, triggered by Juul's financial success. As of September 2018, there were no less than 39 similar Juul devices as well as 15 Juul-compatible pods being offered. Tested show that the pod mods Juul, Bo, Phix, and Suorin contain nicotine salts in a solution with propylene glycol and glycerin.
Nicotine Salt vaping devices are also available in disposable form, multiple brands exist and since their popularity is rising, many new brands of disposable nicotine salt devices are coming to the market. In the United Kingdom, the maximum nicotine concentration allowed by law is 20mg/ml.

## Marketing

Advertisements state nicotine salt liquids contain 2 to 10 times more nicotine than those found in the majority of regular e-cigarette products.

## Trade of nicotine salts

The trade of nicotine salts has grown significantly with the rising popularity of vaping devices and e-cigarettes. Various online retailers offer nicotine salts in different concentrations and formulations, catering to both consumers and manufacturers. In particular, nicotine salts are commonly used in disposable pod systems, which are favored for their higher nicotine content and smoother delivery compared to freebase nicotine.
Recent studies have raised concerns about the potential health risks associated with certain nicotine salt formulations. For example, research published in *Toxics* in January 2024 highlighted that lactic acid salts of nicotine could significantly increase the transfer of toxic metals, such as nickel and chromium, into e-cigarette aerosols. Devices that use lactic acid salts were found to produce much higher concentrations of these metals compared to those using benzoic or levulinic acid salts. This could have implications for both the manufacturing and regulation of nicotine salts, particularly in terms of user safety.