Zyn side effects: what nicotine pouches do to your mouth, heart and sleep

Short answer

The most common Zyn side effects reported in research are irritation where the pouch sits, a faster pulse while the nicotine is being absorbed, and the pull of nicotine dependence. In a controlled study of tobacco-free nicotine pouches, users reported mouth irritation and a higher heart rate during use, and no serious adverse effects (2). A systematic review found that changes in the lining of the mouth at the placement site were common among pouch users, while noting that the research is still limited (3). In January 2025, the FDA authorized the marketing of 20 ZYN products and stated plainly that this "does not mean these tobacco products are safe, nor are they 'FDA approved'" (1).

If you have noticed a sore patch on your gum, a pounding heart after a fresh pouch, or that you feel edgy until the next one goes in, you are not imagining it. Each of these has been described in research, and noticing them is not an overreaction.

Note: this article explains what research and public health agencies say and is not medical advice. It cannot tell you what is happening in your body. Chest pain, shortness of breath or fainting is a reason to call 911. A child who may have swallowed a pouch needs Poison Help at 1-800-222-1222 right away, not an article.

What is Zyn?

Zyn is a brand of nicotine pouch: a small pouch that sits between your gum and lip and releases nicotine through the lining of the mouth. The FDA describes nicotine pouches as "small synthetic fiber pouches containing nicotine designed to be placed between a person's gum and lip" (1).

On January 16, 2025, the FDA authorized the marketing of 20 ZYN nicotine pouch products in ten flavors, each at two nicotine strengths, 3 milligrams and 6 milligrams. Among its key considerations, the agency cited "substantially lower amounts of harmful constituents than cigarettes and most smokeless tobacco products," and the products can be legally marketed in the U.S. to adults 21 and older (1). In the same announcement, the FDA wrote: "There is no safe tobacco product; youth should not use tobacco products and adults who do not use tobacco products should not start."

Is Zyn tobacco?

Zyn pouches contain nicotine but no tobacco leaf; a chemical analysis places ZYN in the category of "tobacco-free nicotine pouches" (7). Legally, they are still treated in the U.S. as tobacco products, and the FDA calls them tobacco products throughout its authorization (1). No tobacco leaf changes the chemistry of the pouch, not what nicotine does to your pulse, sleep and dependence.

Zyn and nicotine pouches side effects: what is known so far

Documented side effects fall into three groups: the mouth, nicotine's effects on the body, and dependence. Very little of this research is specific to the ZYN brand, and none of it has followed users for decades.

The best controlled data come from a 2024 crossover study in which 15 regular smokers used pouches of different strengths, a nicotine-free pouch and a cigarette on separate days; it reported "no serious adverse effects" (2). Its nicotine pouches came from other manufacturers, not ZYN's, and the two stronger ones held far more nicotine than the 3 mg and 6 mg ZYN products authorized in the U.S. (1). Strength varies widely across the market: an analysis of 44 pouches from 20 manufacturers measured between 1.79 and 47.5 mg of nicotine per pouch (8).

Zyn hiccups, nausea and dizziness

Hiccups are one of the most searched Zyn complaints, yet we could not find a study that measured them in pouch users, and they were not among the side effects listed in the controlled study above. Nausea, dizziness and headache were, and none was rated above 3 out of 10 in those experienced users (2). Fainting or a heartbeat that will not settle is a reason to get medical help rather than wait it out (17).

Is Zyn bad for you?

Compared with smoking, the FDA concluded that the authorized ZYN products carry lower risk; compared with not using nicotine, they are not harmless. The products "pose lower risk of cancer and other serious health conditions" than cigarettes and most smokeless tobacco, yet authorization "does not mean these tobacco products are safe" (1).

Which comparison applies depends on where you started. For someone who smoked and switched completely, the lower-risk finding is the relevant one; the FDA notes that the applicant provided evidence that "a substantial proportion of adults who use cigarette and/or smokeless tobacco products completely switched" to the authorized pouches (1). For someone who never used nicotine, the relevant facts are dependence, the oral changes described above, and a faster pulse during use.

Age matters too. The FDA notes that "Nicotine exposure during adolescence can disrupt normal brain development" (6), and in 2024, 1.8% of U.S. middle and high school students reported currently using nicotine pouches (1).

Is Zyn bad for your heart?

Nicotine from a pouch raises your heart rate while it is being absorbed, and its long-term effect on the heart in pouch users has not been studied.

In the 2024 crossover study, which used other brands' pouches, heart rate rose by about 12 bpm with the 20 mg pouch and 25 bpm with the 30 mg pouch, against about 27 bpm after a cigarette; the 6 mg pouch, the strength closest to authorized ZYN products (3 mg and 6 mg), raised it only slightly. The authors wrote that "Effects on systolic and diastolic blood pressure were minor for all study arms," while central systolic pressure rose early in use with the high-dose pouches and the cigarette (2).

For the longer view, a review of nicotine's cardiovascular safety concluded that "the risks of nicotine without tobacco combustion products (cigarette smoke) are low compared to cigarette smoking, but are still of concern in people with cardiovascular disease" (5). That comes from nicotine medicines and smokeless tobacco, not years of pouch use; with a heart condition or high blood pressure, nicotine in any form is a topic for your clinician. Our article on nicotine, vaping, heart rate and sleep goes deeper into the pulse side.

A faster pulse after a pouch is expected; some symptoms are not. Chest pain or discomfort, shortness of breath, feeling weak, light-headed or faint, or pain in the jaw, neck, back, arms or shoulders are the CDC's heart attack symptoms, and its instruction is to "call 9-1-1 immediately" (18). A racing or irregular heartbeat that does not settle once the nicotine wears off is a reason to call a clinician the same day; the NHLBI lists dizziness and fainting among arrhythmia symptoms and advises emergency care for very serious ones such as chest pain or difficulty breathing (17). Our guide to heart arrhythmia and palpitations explains what an irregular heartbeat can mean.

Does Zyn cause cancer?

No study has shown that Zyn causes cancer, and none has followed users long enough to show that it does not. Pouches are too new for cancer studies in their users, so the answer rests on what they contain.

Nicotine itself is not what makes tobacco so deadly. The FDA states that "it's the thousands of chemicals contained in tobacco and tobacco smoke that make tobacco use so deadly" (6).

Traditional smokeless tobacco is a different product. The National Cancer Institute states that "Smokeless tobacco causes oral cancer, esophageal cancer, and pancreatic cancer," and names tobacco-specific nitrosamines (TSNAs), which form as tobacco is grown, cured, fermented and aged, as its most harmful chemicals (9). Pouches made without tobacco leaf skip those steps, although testing has still found traces of TSNAs in some pouches.

What has been measured in pouches. A laboratory comparison found no nitrosamines or polycyclic aromatic hydrocarbons in two ZYN products, low levels of ammonia, chromium, formaldehyde and nickel, and a number of harmful and potentially harmful constituents similar to nicotine gum and lozenges (7). Its authors work for Swedish Match, the company that makes ZYN, which is worth knowing when weighing it. An independent analysis of 44 pouches from 20 manufacturers detected TSNAs in 26, at up to 13 ng of the carcinogen N-nitrosonornicotine per pouch, and called this "of serious concern" (8). Its published summary does not break results down by brand.

The regulator's reading. The FDA concluded that authorized ZYN products pose lower cancer risk than cigarettes and most smokeless tobacco (1): a comparison, not a guarantee of zero risk.

Does Zyn cause mouth cancer?

We found no study linking Zyn or other nicotine pouches to mouth cancer, and none has followed users long enough to rule it out. What researchers have seen are changes where the pouch sits: in a small case series, all five pouch users examined had white lesions at the placement site, and tissue samples showed thickened, inflamed lining (4). Those findings are not cancer. But a systematic review notes that in one study, which grouped snus and pouch users together, the white changes resembled smokeless tobacco keratosis, a condition that may have the potential to progress to oral cancer, and its authors write that the malignant potential of such lesions "is still of concern" (3). What matters in practice are the warning signs: the National Institute of Dental and Craniofacial Research lists a sore, lump or thick patch, a white or red patch, pain or bleeding, or numbness in the mouth, and says that if any lasts "more than two weeks, see a dentist or a doctor" (19).

Are Zyn pouches bad for your gums?

Nicotine pouches are linked to changes in the gum and mouth lining where they are placed, and the long-term effect on gum health is not yet known. A 2024 systematic review found that "Oral mucosal changes at the site of placement were common among NP users," from slight wrinkling to various white lesions, seemingly related to how many pouches people used per day and for how long. Dry mouth, soreness, gingival blisters and a strange jaw sensation were also reported (3).

The evidence is thin. Only three studies, with 190 participants, met the review's criteria, all judged at high risk of bias, and the authors called the research "currently limited" (3). The case series that examined tissue under the microscope looked at five people (4).

Your dentist is the right person to look; say where you usually place pouches. A patch, sore or bleeding that lasts more than two weeks needs a dentist or doctor (19).

What happens if you swallow a Zyn pouch?

For an adult who swallows one pouch by accident, research does not describe what typically happens; for a small child, it can be a poisoning and needs a call to Poison Help right away.

An analysis of 134,663 nicotine ingestions in children under 6 reported to U.S. poison centers from 2010 to 2023 found that the rate of nicotine pouch ingestions rose by 763.1% from 2020 to 2023. Pouches were more likely than other product formulations combined to be associated with a serious medical outcome (odds ratio 1.53) or hospital admission (odds ratio 2.03). Across all nicotine products in the analysis, most ingestions involved children under 2, at home (10).

If a child may have put a pouch in their mouth or swallowed one, call Poison Help at 1-800-222-1222. The line is toll-free and available 24/7 (11). If the child has trouble breathing, has a seizure or cannot be woken, call 911. Poison Help also takes calls about adults, so the same number is a place to start if you swallowed a pouch and feel unwell. Keep cans closed and out of reach, and dispose of used pouches where a child cannot find them.

Can you swallow Zyn spit?

No study has looked at swallowing saliva while using a nicotine pouch, so there is no research-based answer either way. In the controlled pouch study, users did not produce extra saliva and reported a slightly drier mouth (2). If nausea or hiccups bother you, note when they happen and mention it to your clinician.

Sleep and anxiety between pouches

Research in people who smoke links nicotine to poorer sleep and to tension that builds between doses; pouch users have not been studied directly.

Sleep. A review of 52 studies found that nicotine use was associated mainly with symptoms of insomnia: taking longer to fall asleep, more fragmented sleep, less deep (slow-wave) sleep, lower sleep efficiency and more daytime sleepiness, along with suppressed REM sleep (12). A pouch kept in late in the evening, or used when you wake in the night, puts nicotine into the hours you are trying to sleep. Our article on waking up at 3 a.m. and not falling back asleep looks at the stress side of broken nights.

The calm a pouch seems to bring. Andy Parrott's review found that smokers' moods were normal while smoking and worsened between cigarettes, and concluded that "the apparent relaxant effect of smoking only reflects the reversal of the tension and irritability that develop during nicotine depletion" (13).

After stopping. A meta-analysis of 26 studies found that quitting smoking was associated with reduced anxiety, depression and stress, and better positive mood, compared with continuing to smoke (14). These are observational studies, so they show an association, not proof for any one person.

Where self-observation stops. Anxiety with chest pain, shortness of breath or fainting is not something to chart; call 911 (18). If anxiety or low mood is constant, or you have thoughts of harming yourself, contact a clinician, or call or text 988.

Is Zyn better than vaping?

We found no study comparing the health effects of Zyn and vaping head to head, so the evidence does not show either one to be better. A vape delivers nicotine as an aerosol you inhale; a pouch delivers it through the lining of the mouth. Both deliver nicotine, so both carry a risk of dependence.

The FDA's lower-risk conclusion for ZYN compares it with cigarettes and most smokeless tobacco, not with e-cigarettes (1). A pouch is also not automatically "lighter" on nicotine: in the crossover study, a 30 mg pouch from another brand, five times the strongest authorized ZYN product, reached a peak blood nicotine level of 29.4 ng/mL, against 15.2 ng/mL for a cigarette (2). This article does not recommend one product over the other; if you are weighing them, or weighing quitting, that is a conversation for you and your clinician.

Zyn withdrawal symptoms and how to quit Zyn

Withdrawal from pouches has not been studied on its own, but nicotine withdrawal in general is well described and usually peaks in the first week. A review of tobacco abstinence research identified anger, anxiety, depression, difficulty concentrating, impatience, insomnia and restlessness as valid withdrawal symptoms with that time course, and listed constipation, cough, dizziness, increased dreaming and mouth ulcers as possible abstinence effects (15).

Where to get support. The CDC lists the free U.S. quitline, 1-800-QUIT-NOW, among its resources for quitting, and notes that "Quitlines provide free coaching over the phone" (16). Whether any quitting method or medicine suits you is a decision for you and your clinician; this article gives no product choices or doses.

Some symptoms are not withdrawal. Chest pain, fainting or shortness of breath does not, and needs a 911 call (18). Low mood that deepens rather than lifts after the first weeks is a reason to speak to a clinician.

Zyn and nicotine pouches: the questions people ask next

Is it okay to use a Zyn before a workout?

Nicotine raises heart rate at rest: in the controlled pouch study, by up to about 25 bpm with a 30 mg pouch from another brand, while the 6 mg pouch raised it only slightly (2). We found no study of pouches and exercise. If you have a heart condition or high blood pressure, ask your clinician whether nicotine before exercise is a concern, since a cardiovascular review flags nicotine as a concern in people with cardiovascular disease (5). Chest pain or difficulty breathing during exercise means stopping and calling 911 (18).

Can I use Zyn while pregnant?

The FDA states that "Nicotine can cross the placenta when a pregnant person uses tobacco products," and links this to possible harms including premature labor, low birth weight and sudden infant death syndrome (6). Nicotine pouches have not been studied in pregnancy, but the FDA's statement covers nicotine from tobacco products generally, and ZYN is regulated as one. If you are pregnant, planning a pregnancy or breastfeeding and use pouches, tell your obstetric clinician or midwife what you use and how often; decisions about stopping belong in that conversation.

Is it bad to fall asleep with a Zyn in?

No study has looked at sleeping with a nicotine pouch in your mouth, but two findings are relevant. Nicotine use is linked to taking longer to fall asleep, more fragmented sleep and less deep sleep (12), so nicotine at bedtime works against the sleep you want. And mouth-lining changes at the placement site seemed related to how many pouches people used and for how long (3), so hours of overnight contact are worth mentioning to your dentist. A pouch left on a nightstand is also within reach of small children (10).

I only use a few pouches a day. Can I still get addicted?

It is possible. Dependence comes from the nicotine itself, and we found no research that sets a number of pouches below which it cannot develop. The FDA describes nicotine as the reason tobacco products are addictive and notes that it "can change the way the brain works, causing cravings for more of it" (6). A useful self-check is how you feel between pouches. Parrott's review describes moods worsening between doses and returning to normal with the next one (13). If the next pouch feels less like a choice and more like a fix for edginess, that is the pattern the research describes.

Will my mouth heal if I stop using Zyn?

Research has not answered this yet. The systematic review on nicotine pouches and oral health included no study that followed mouth changes after people stopped using pouches; the closest was a study without a control group in which existing lesions in snus users decreased after they switched to pouches, which the authors say should be read cautiously (3). A practical approach is to ask your dentist to look at the placement site now and again a few weeks after you stop or change where you place pouches, so there is a before and after on record. Any patch, sore or lump lasting more than two weeks needs a dentist or doctor regardless (19).

Is this forever?

The physical part of nicotine withdrawal is not. In research on tobacco abstinence, the main withdrawal symptoms peak in the first week and last two to four weeks (15). Cravings can return later in specific situations, which is one reason the free 1-800-QUIT-NOW quitline exists (16). For anxiety, the longer-term association runs in an encouraging direction: quitting smoking has been linked with reduced anxiety, depression and stress over the following months and years (14). Whether the same holds for pouches has not been studied.

When to see a doctor or dentist

You do not need a symptom to bring up pouches with a clinician, but some signs mean booking a visit, and a few mean calling 911.

Call 911 for chest pain or discomfort, shortness of breath, feeling faint, or pain spreading to the jaw, neck, back or arms (18). Call Poison Help at 1-800-222-1222 if a child may have swallowed or chewed a pouch (11). Call a clinician the same day if a racing or irregular heartbeat does not settle after the nicotine wears off, especially with dizziness (17). See a dentist or doctor if a sore, white or red patch, lump, bleeding or numbness in your mouth lasts more than two weeks (19).

What to say. One sentence is enough: "I use nicotine pouches, about [how many] a day, usually on the [left/right, upper/lower] gum, and I want to know whether they are affecting my [heart / sleep / mouth]." That gives the product, amount, placement and question.

What to bring.

• The brand and strength you use, since pouch strengths range widely (8).

• Any other nicotine you use: cigarettes, vapes, gum or lozenges.

• A short note of what you have noticed and when: a sore spot, a racing heart after a fresh pouch, bad nights, edginess between pouches.

• Your medicines, including anything over the counter.

What to ask.

• "Is nicotine a concern with my heart, my blood pressure or my medicines?"

• "Can you check the place in my mouth where I put the pouches?"

• "If I want to stop, what support is available to me?" The CDC lists the free quitline 1-800-QUIT-NOW (16).

Start understanding your body

Learn what affects your energy, stress, sleep, and daily state. Get the app.

Explore your data

How Welltory helps — and what it cannot do

The limits first. Welltory is a general wellness product, not a medical device. It does not diagnose, detect, predict, monitor, prevent, treat or mitigate nicotine dependence, heart conditions, oral lesions or any other condition. It cannot tell whether you used a pouch, cannot see your gums, and cannot tell you whether nicotine is harming you. It can help you keep a dated record more reliable than memory.

You note the pouch; the app is already recording heart data. When Welltory flags a stress stretch and asks "What happened?", you can tap a suggested tag, type a few words or just talk: "Zyn", "fresh pouch", "pouch before bed", "no nicotine today", "craving", "quit day 3". The app does not know you used nicotine. You do, and you put it on the record.

Then look at the days side by side. Resting heart rate, HRV, stress minutes, sleep analysis and Battery are recorded the same way on days with and without pouches. Put your tags beside them and you have a dated diary: what you did, and what was being measured at the time. These are your own numbers against your own history, not a population range and not a line marked normal. Stress minutes, sleep analysis and Battery need a supported wearable.

After a few weeks of tagging, My Patterns has something to work with. My Patterns collects the tags you add to stress and rest stretches on the Today screen, so it needs iOS with an Apple Watch or Oura. Patterns appear at around seven tagged events in the current month, with some history from the month before. It shows which tagged situations tend to come alongside stressful stretches, which tags do not happen often but hit your body hard, trends by day of week, heart-rate data, and every time a tag occurred.

That record is what you take to the appointment. The Journal (Premium) keeps your measurements, tags and notes, and from the Welltory web app you can export a CSV (Dashboard → choose a chart → Export). If you are stopping, the same tags show your clinician how the first weeks went. It is a record you made, not a conclusion the app reached. Any pattern in it is an association to discuss with your doctor, not proof that nicotine caused anything.

The red flags belong here too, in the same type size: chest pain, shortness of breath or fainting means calling 911, not adding a tag (18). A racing or irregular heartbeat that does not settle means calling a clinician the same day (17). A child who may have swallowed a pouch means calling Poison Help at 1-800-222-1222 (11). A mouth sore or patch lasting more than two weeks means seeing a dentist or doctor (19).

Where to find other people in the same situation. If you are also living with an energy-limiting condition, Welltory runs a paid, moderated community called Energy Lab for women aged 18 to 65 living with ME/CFS, long COVID, fibromyalgia, POTS, MCAS and similar. It runs alongside the app: you keep collecting your own data, and the Lab is where people learn to read it together, with a medical board answering the science. It is education and peer support, not medical care, it does not replace your clinician, and there is a 14-day money-back guarantee on a first purchase.

How we made it

Made with AI tools, then edited and fact-checked by the Welltory team. See our Editorial & AI policy.

Data analysis by Jane Smorodnikova, co-founder of Welltory and the person who built the methodology behind how we read physiological data.

Written by Tatsiana Yashyna.

Discounts for blog readers: up to 36% off

See what affects your energy, stress, sleep, and daily state with Welltory

Explore your data