Using nicotine gum/nicotine lip pouch if one does not smoke or vape.
Question

I do not smoke or vape but I do use nicotine gum as I find it to be relaxing, is this halal?
Praise be to Allah.Firstly:
Nicotine is an organic, semi-alkaline, toxic compound and is considered one of the most harmful substances found in tobacco. .It is the substance that causes addiction in smokers
Secondly:
Nicotine gum is a medical gum taken orally under prescription and medical supervision, providing a dose of nicotine. Its purpose is to replace the nicotine that individuals might get from smoking cigarettes or other tobacco products during withdrawal symptoms, thereby reducing their severity. While the gum contains the chemical responsible for cigarette addiction, nicotine, it does not contain other harmful substances such as tar and also does not cause intoxication. Nicotine gum works to alleviate the severity of nicotine withdrawal symptoms because it compensates the body for the nicotine that is withdrawn due to the sudden cessation of smoking.
Despite its benefits and effectiveness in quitting smoking, incorrect use may lead to an alternative addiction to cigarette nicotine, thus entering an endless cycle of nicotine.
Nicotine gum: how to use it and how to avoid addiction to it? - At-Ta`afi Hospital (altaafi.com)
This gum has harmful side effects if not used under a doctor's supervision.
"Some harms appear in case of incorrect use and non-adherence to the specified dose, the most prominent of which are:
- Pain in the mouth, teeth, or jaw.
- Feeling dizzy.
- Nausea and vomiting.
- Severe diarrhea.
- Weakness and lethargy.
- Rapid heartbeat.
- Difficulty breathing.
- Appearance of a skin rash.
- Presence of blisters in the mouth." End quote from:
Benefits, harms, and price of nicotine gum, the easiest drug to quit smoking | Bareeq Hospital (bareeqeg.com)
Thirdly:
 If Allah has spared you from smoking, then you are bringing harm upon yourself by using this gum, and it may lead to addiction to it. The basic  principle is the prohibition of what is harmful; as Allah says (interpretation of the meaning): {And do not kill yourselves [or one another]. Indeed, Allah is to you ever Merciful.} (An-Nisa': 29), and He says (interpretation of the meaning): {And do not throw [yourselves] with your [own] hands into destruction. And do good; indeed, Allah loves the doers of good.} (Al-Baqarah: 195).
And the Prophet (peace and blessings be upon him) said: "There should be neither harming nor reciprocating harm." Narrated by Ahmad and Ibn Majah (2341) and authenticated by Al-Albani in Sahih Ibn Majah.
Also, spending a lot of money on it is considered extravagance or wastefulness, and both extravagance and wastefulness are prohibited; as Allah says (interpretation of the meaning): {And eat and drink, but be not excessive. Indeed, He likes not those who commit excess.} (Al-A`raf: 31)
And He dispraised wastefulness, saying (interpretation of the meaning): {And give the relative his right, and [also] the poor and the traveler, and do not spend wastefully. Indeed, the wasteful are brothers of the devils, and ever has Satan been to his Lord ungrateful.} (Al-Isra': 26),
Even if you adhere to a dose that does not cause harm and do not spend a lot of money on it, there is still a fear of becoming addicted to it. Therefore, the advice is to stay away from it, and in the permissible good things, there is sufficiency.
And Allah knows best.