Researched and written by ChatGPT
Nicotine has a terrible reputation because it has been welded, culturally and medically, to cigarettes.
But nicotine is not cigarette smoke.
That distinction matters.
Cigarette smoke contains thousands of chemicals, including known carcinogens and combustion byproducts. Nicotine replacement therapies, such as patches, gum, and lozenges, deliver nicotine without burning tobacco.
That does not make nicotine harmless. It does mean it can be studied separately.
And now, one of the most interesting places nicotine is being discussed is in relation to long COVID.
Why Would Nicotine Even Be Considered for Long COVID?
Long COVID is not one simple condition.
People report combinations of:
fatigue
brain fog
dizziness
shortness of breath
palpitations
sleep disruption
muscle pain
post-exertional crashes
altered taste or smell
gut issues
anxiety-like nervous system symptoms
Researchers are still debating the causes. Some proposed mechanisms include immune dysregulation, viral persistence, microclotting, mitochondrial dysfunction, autonomic nervous system disruption, and inflammation.
Nicotine enters the conversation because it interacts with the nicotinic acetylcholine receptors, often shortened to nAChRs.
These receptors are involved in attention, memory, autonomic function, inflammation, and communication between the nervous system and immune system.
Some researchers have proposed that SARS-CoV-2, or pieces of the virus such as the spike protein, may interfere with this cholinergic system. If that is true, then nicotine could theoretically help by stimulating or modulating those receptors.
That is the hypothesis.
It is not yet proof.
The 2023 Case Report
One of the main papers often cited in this discussion was published in 2023 by Leitzke and colleagues.
The authors treated several people with post-COVID syndrome using nicotine patches and reported improvements in symptoms.
That sounds promising, but it is important to understand what kind of evidence this is.
This was not a large randomized controlled trial.
It was a small clinical report.
There was no large placebo group. There was no blinding. There was no way to fully separate the effects of nicotine from time, expectation, natural recovery, or other variables.
Still, small reports matter when a condition has limited treatment options. They do not prove a treatment works, but they can point researchers toward something worth investigating.
The 2025 Cholinergic Disruption Theory
In 2025, Leitzke published a review arguing that long COVID may involve disruption of the cholinergic system, especially nicotinic acetylcholine receptors.
The paper reviews how these receptors are involved in multiple systems affected in long COVID, including:
the brain
the autonomic nervous system
immune signaling
blood vessels
oxygen handling
inflammation
The central idea is that nicotine may help “unblock” or restore function in these receptor pathways.
This is an interesting theory because it tries to connect many long COVID symptoms through one biological system.
But again, this is still a theory.
A review paper can explain a mechanism. It cannot prove that nicotine patches successfully treat long COVID in real-world patients.
What About ACE2 and the Spike Protein?
SARS-CoV-2 uses the ACE2 receptor as one route into human cells.
That much is well established.
Some nicotine discussions go further and suggest nicotine may block spike protein, protect ACE2, or prevent spike-related damage.
This is where caution is needed.
There are laboratory and theoretical discussions about nicotine, ACE2, nicotinic receptors, and spike protein interactions. But there is no solid clinical evidence showing that nicotine patches repair ACE2 receptors or prevent spike proteins from binding in humans.
That does not mean the idea is impossible.
It means the evidence is not strong enough yet to present it as fact.
Why the Patch?
The patch is getting attention because it provides slow, steady nicotine exposure through the skin.
This is different from smoking or vaping, which create rapid nicotine spikes.
A patch avoids combustion, avoids inhalation, and delivers a more controlled dose.
That makes it more suitable for medical research.
However, nicotine patches can still cause side effects, especially in people who do not normally use nicotine.
Common side effects include:
nausea
dizziness
headache
vivid dreams
insomnia
skin irritation
sweating
increased heart rate
jitteriness
A systematic review of transdermal nicotine use in non-smokers found that nausea and skin itching were among the most common side effects, and about 7.1% of non-smokers stopped treatment because of adverse effects.
That matters.
A compound can be interesting and still require caution.
What Do Skeptics Say?
Skeptics make a fair point: the evidence is still thin.
Some people online report major improvements. Others report no change. Some say they felt worse.
Anecdotes can be useful signals, especially when patients are dealing with an under-treated condition. But anecdotes are not enough to determine whether a treatment works.
The McGill Office for Science and Society reviewed the nicotine patch trend in 2025 and concluded that the current evidence is not strong enough to support broad claims. They noted that nicotine patches might help some people, but the mechanism remains uncertain and the long-term safety of this use is unclear.
That is a reasonable criticism.
It does not shut the door.
It simply says: do not confuse early signals with settled science.
Where the Evidence Stands Right Now
Here is the honest state of the evidence:
Nicotine patches for long COVID are:
biologically plausible
supported by small human case reports
supported by a proposed receptor-based mechanism
interesting enough to deserve proper clinical trials
But they are not yet:
proven as a long COVID treatment
approved specifically for long COVID
shown to repair ACE2
shown to clear spike protein
proven safe for long-term use in this context
That distinction matters.
Final Thought
Nicotine may turn out to be one of those molecules that was dismissed too quickly because of its association with cigarettes.
But the opposite mistake would be just as careless: treating nicotine as a miracle treatment before the evidence is mature.
The reasonable position is curiosity with boundaries.
Nicotine patches deserve further study for long COVID.
They may help some people.
They may do nothing for others.
They may worsen symptoms in some.
Right now, the science is not finished.
But it is definitely interesting.
Links and Sources
Leitzke et al., 2023 — post-COVID syndrome and nicotine patch report
https://pubmed.ncbi.nlm.nih.gov/36650574/Full text, 2023 paper
https://pmc.ncbi.nlm.nih.gov/articles/PMC9845100/Leitzke, 2025 — long COVID and cholinergic receptor disruption review
https://pubmed.ncbi.nlm.nih.gov/40011942/Full text, 2025 review
https://link.springer.com/article/10.1186/s42234-025-00167-8Dautzenberg et al., 2021 — transdermal nicotine in non-smokers systematic review
https://pmc.ncbi.nlm.nih.gov/articles/PMC8183099/ScienceDirect abstract — adverse effects in non-smokers
https://www.sciencedirect.com/science/article/abs/pii/S2590041221000337Mills et al., 2010 — adverse events associated with nicotine replacement therapy
https://pmc.ncbi.nlm.nih.gov/articles/PMC2917405/McGill Office for Science and Society, 2025 — skeptical review of nicotine patches for long COVID
https://www.mcgill.ca/oss/article/medical-health-and-nutrition-pseudoscience/strange-story-nicotine-patches-treat-long-covidClinicalTrials.gov — nicotine patch study in acute COVID-19, not long COVID
https://clinicaltrials.gov/study/NCT04608201
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