Nicotine has measurable effects on muscle tissue, but the direction of those effects depends heavily on how nicotine enters your body. Cigarette smoking clearly impairs muscle protein building and accelerates muscle breakdown, yet when researchers study nicotine in isolation, stripped of the thousands of other chemicals in tobacco smoke, the results become more complicated and sometimes contradictory. For anyone using nicotine pouches, vaping, or smokeless tobacco while trying to build muscle, the honest answer is that the science points in several directions at once.
Smoking and Muscle Protein Synthesis
The strongest evidence for nicotine-related muscle harm comes from studies of cigarette smokers. A study comparing long-term smokers (at least 20 cigarettes a day for 20-plus years) with matched nonsmokers found that the rate at which smokers built new muscle protein was roughly 40% lower than in nonsmokers. Smokers also showed about a third more expression of myostatin, a protein that actively inhibits muscle growth, and about 45% more expression of MAFbx, a molecule involved in tagging muscle proteins for breakdown.1American Journal of Physiology – Endocrinology and Metabolism. Smoking impairs muscle protein synthesis and increases the expression of myostatin and MAFbx in muscle In other words, smoking appears to hit muscle from both sides: slowing the building process while ramping up the dismantling process.
Lab studies on muscle cells paint a similar picture. When skeletal muscle cells were exposed to cigarette smoke extract, they shrank in diameter, and a key structural protein (myosin heavy chain) broke down in a dose-dependent manner. The mechanism involved a surge in oxidative stress that triggered a signaling cascade leading to activation of the same muscle-breakdown machinery seen in the human smokers.2PubMed. Cigarette smoke and muscle catabolism in C2 myotubes The consistent theme across these studies is that cigarette smoke ramps up the cellular pathways responsible for chewing through muscle protein.
Nicotine Alone Is a Different Story
Here is where the picture gets genuinely confusing. A cigarette delivers nicotine alongside carbon monoxide, tar, formaldehyde, and thousands of other compounds. When researchers test nicotine by itself on muscle cells, the results sometimes flip. One study found that nicotine actually promoted the maturation of muscle precursor cells by turning up the activity of key muscle-building regulators called MyoD and Myogenin. The researchers then injected nicotine into injured leg muscles of obese mice and found those muscles regenerated faster than muscles that received a saline injection.3PubMed. Nicotine promotes the differentiation of C2C12 myoblasts and improves skeletal muscle regeneration in obese mice
That finding might seem to suggest nicotine is good for muscle, but the context matters. The mouse model specifically involved obesity-related impairments in muscle repair. Whether nicotine would have the same regenerative effect in lean, healthy muscle tissue is unclear. And cell-culture experiments, while useful for understanding mechanisms, do not automatically translate to what happens in a living person using nicotine pouches at the gym. The study is a useful signal that nicotine alone does not always damage muscle in the way cigarette smoke does, but it is not a green light.
Hormonal Ripple Effects
Nicotine triggers a cascade of hormonal changes that could indirectly affect how well you build or maintain muscle. Smoking higher-nicotine cigarettes significantly raised circulating levels of cortisol, growth hormone, and prolactin compared with lower-nicotine cigarettes, and those hormone levels remained elevated at least an hour after smoking.4PubMed. Nicotine from cigarette smoking increases circulating levels of cortisol, growth hormone, and prolactin in male chronic smokers The growth hormone bump might sound appealing if you are trying to add muscle, but the cortisol spike works against you. Cortisol is catabolic, meaning it promotes the breakdown of tissue, including muscle. Chronically elevated cortisol is one of the established mechanisms behind muscle wasting in a variety of conditions.
Whether these hormonal swings from nicotine use (as opposed to cigarette smoking) are large enough and sustained enough to materially change your muscle-building trajectory is hard to pin down. The acute elevations from a single dose may not matter much, but habitual use that keeps cortisol chronically nudged upward could theoretically blunt your gains over months or years. No controlled long-term human study has isolated that variable, so the honest framing is that the hormonal profile is not clearly favorable for someone prioritizing muscle growth.
Does Nicotine Help or Hurt Exercise Performance?
If nicotine made you meaningfully stronger or more endurant, that could offset some of its downsides by letting you train harder. A review that examined ten studies on nicotine (delivered through medication or smokeless tobacco, not cigarettes) and exercise performance found a mostly flat result: seven studies reported no change, two found a small performance boost, and one found performance got worse.5PubMed Central. Nicotine: Sporting Friend or Foe? A Review of Athlete Use, Performance Consequences and Other Considerations The review covered tests of muscular strength, power, and endurance, so the lack of effect is not limited to just one type of exercise.
A separate study tested snus, the Swedish oral tobacco product popular among some athletes, and found that despite increasing blood flow to the brain and muscles, it did not change how long participants could exercise at a moderate intensity or how hard the effort felt.6PubMed Central. The effects of oral smokeless tobacco administration on endurance performance The bottom line on acute performance: nicotine is not reliably helping you push harder in a workout, so there is no training-quality argument to offset the potential downsides.
Body Composition and Appetite
One of the most consistent effects of nicotine, and the reason some people are drawn to it outside of addiction, is its influence on body weight and fat. In rats, self-administered nicotine suppressed weight gain and reduced body fat percentage without altering the percentage of lean mass.7PubMed Central. Self-administered nicotine increases fat metabolism and suppresses weight gain in male rats A review of the underlying mechanisms found that nicotine decreases appetite and food intake by altering signaling molecules in the brain’s appetite-control center, and it independently increases energy expenditure.8PubMed. Nicotine and energy balance: A review examining the effect of nicotine on hormonal appetite regulation and energy expenditure
For someone focused on muscle growth, the appetite-suppressing effect is a double-edged sword. Building muscle requires a caloric surplus or at least adequate protein intake. If nicotine is dampening your hunger enough that you consistently eat less, you may be undermining the nutritional foundation needed for muscle repair and growth. The fat-loss effect sounds attractive during a cutting phase, but if your goal is to maximize hypertrophy, anything that makes it harder to eat enough is working against you in a practical sense that has nothing to do with molecular biology.
Tendon and Connective Tissue Healing
Muscle growth does not happen in a vacuum. Your tendons, which connect muscles to bones, and other connective tissues need to adapt alongside your muscles, especially when you are training hard. Nicotine appears to be meaningfully harmful to tendon healing, and this matters even if you are not a cigarette smoker.
In a rat model, nicotine exposure led to tendons that were weaker, less stiff, and smaller in cross-sectional area after an injury, compared with controls.9PubMed Central. Nicotine Impairs Intra-Substance Tendon Healing After Full Thickness Injury in a Rat Model A follow-up study that specifically compared cigarette smoke exposure with e-cigarette vapor found that the vaping group actually had the weakest tendons of all three groups (including the cigarette group). The tendons in the control group could withstand an average load of about 41 newtons before failing; the cigarette group averaged about 37 newtons; the vaping group averaged about 32 newtons.10Arthroscopy – Journal of Arthroscopic and Related Surgery. Nicotine Exposure Via Electronic Cigarettes Significantly Impedes Biomechanical Healing Properties of Tendon Healing in a Rat Model The finding that e-cigarette nicotine was at least as bad as cigarette smoke for tendon healing suggests that it is the nicotine itself, not just the combustion byproducts, doing the damage.
If you train with enough intensity to occasionally strain or micro-tear tendons (which is common in progressive resistance training), impaired tendon healing could create a bottleneck. Stronger muscles pulling on slower-healing connective tissue is a recipe for overuse injuries, which can sideline training for weeks or months.
Mitochondrial Function
Your muscles rely on mitochondria to produce the energy needed for contraction and recovery. Nicotine has been shown to alter mitochondrial structure in ways that favor fragmentation over the normal balance of fission and fusion. In cells from smokers and asthmatics, nicotine exposure increased the proteins that break mitochondria apart while decreasing those that keep them fused together, and this correlated with blunted energy production through oxidative phosphorylation.11American Journal of Physiology – Lung Cellular and Molecular Physiology. Nicotine affects mitochondrial structure and function in human airway smooth muscle cells While this study focused on airway smooth muscle rather than skeletal muscle, the mitochondrial machinery is shared across cell types, and disrupted energy production in muscle cells would logically impair both training capacity and recovery.
Sarcopenia and Long-Term Muscle Loss
The long-term picture for smokers is concerning. A large cross-sectional study of people aged 60 and older found that current smokers had roughly 80% higher odds of sarcopenia (age-related muscle loss) compared with people who had never smoked, after adjusting for factors like age, sex, alcohol use, and medical history. The risk climbed with years of smoking: those who had smoked for more than 40 years had substantially elevated odds.12PubMed Central. Effects of cigarette smoking associated with sarcopenia in persons 60 years and older: a cross-sectional study in Zhejiang province Multiple epidemiological studies have linked cigarette smoking to increased rates of sarcopenia in older adults.13PubMed. Sarcopenia and smoking: a possible cellular model of cigarette smoke effects on muscle protein breakdown
That said, the evidence is not perfectly unanimous. A smaller study that measured actual psoas muscle size on CT scans across nonsmokers, passive smokers, and active smokers found no statistically significant differences in muscle cross-sectional area between the groups after adjusting for body size, sex, and age.14Tobacco Induced Diseases. The association between cigarette smoking exposure and sarcopenia assessed by Psoas Muscle Index: A secondary data analysis The discrepancy likely reflects differences in study design, sample size, and how sarcopenia was defined. The weight of the epidemiological evidence still tilts toward smoking being harmful for long-term muscle maintenance, but the relationship is clearly influenced by how much and how long someone has smoked.
An important caveat: nearly all the long-term data involve cigarette smokers, not people using nicotine in isolation. Whether someone who uses nicotine pouches or patches for decades would face the same sarcopenia risk is genuinely unknown. The mechanisms identified in the protein synthesis studies point to both nicotine-specific and smoke-specific pathways, so the answer is unlikely to be a clean “no risk.”
How Quickly Things Improve After Quitting
If you currently smoke and are concerned about your muscle health, the recovery timeline is encouragingly fast for at least some measures. A study found that just 14 days of smoking cessation improved skeletal muscle fatigue resistance, meaning participants could sustain repeated muscle contractions longer before their force output dropped. The improvement coincided with carbon monoxide levels in the blood returning to those seen in nonsmokers, suggesting that better oxygen delivery was part of the explanation.15PubMed Central. Fourteen days of smoking cessation improves muscle fatigue resistance and reverses markers of systemic inflammation Systemic inflammation markers also fell. Two weeks is not enough time to reverse years of impaired protein synthesis or accumulated muscle loss, but the speed of functional improvement suggests that the body is eager to recover once the insult stops.
Why the Delivery Method Matters More Than You Think
The recurring theme across this research is that cigarette smoke and nicotine are not interchangeable variables, yet they are not entirely separable either. Cigarette smoke contains carbon monoxide, which directly impairs oxygen transport to muscles. It contains free radicals that drive the oxidative stress and protein breakdown seen in cell studies. It contains volatile compounds that trigger systemic inflammation. Nicotine contributes its own effects on top of all of that: the cortisol increase, the appetite suppression, the tendon-healing impairment, the mitochondrial disruption.
For someone who vapes or uses nicotine pouches, you are removing most of the combustion-related damage but keeping the nicotine-specific effects. That is likely better than smoking for muscle health, but the tendon data suggest it is not neutral. The one animal study showing nicotine-promoted muscle regeneration is intriguing but was conducted in an obese mouse model with impaired healing, a context far removed from a healthy person trying to optimize hypertrophy.
Nicotinic receptors are present on skeletal muscle tissue, which is how the neuromuscular junction works: your nerves communicate with your muscles through acetylcholine acting on nicotinic receptors.16PubMed. The isolation and characterisation of the nicotinic acetylcholine receptor from human skeletal muscle Flooding those receptors with exogenous nicotine does not simply amplify normal signaling. With sustained exposure, nicotinic receptors can desensitize, essentially going offline despite the continued presence of the agonist.17PubMed Central. Structural mechanism of muscle nicotinic receptor desensitization and block by curare The functional consequences of chronic low-level receptor desensitization from habitual nicotine use on muscle contraction and growth signaling remain an open question that the current research has not directly answered.
Practical Framing for People Who Train
If you smoke cigarettes and lift weights, the evidence is fairly unambiguous: smoking is actively working against your muscle-building goals through multiple simultaneous mechanisms. Quitting produces measurable functional improvements within two weeks, so the cost-benefit calculation is straightforward.
If you use nicotine through non-combustion methods, the picture is murkier. You are not dealing with the carbon monoxide or the heavy oxidative stress load from smoke, but you are still potentially suppressing your appetite (making it harder to eat enough to grow), raising your cortisol, impairing your tendon healing, and exposing your mitochondria to structural disruption. No controlled study has tracked a group of nicotine-pouch users through a structured resistance-training program to measure actual hypertrophy outcomes. The absence of that data means anyone telling you definitively that nicotine pouches “don’t affect gains” is guessing, and anyone telling you they “destroy gains” is also guessing. The mechanistic evidence suggests a mild headwind rather than a hard wall, but quantifying that headwind in real-world terms is beyond what the current science can do.