Acupuncture is broadly safe when performed by a trained, licensed practitioner, but it is not risk-free. A large meta-analysis of prospective studies found that roughly one in ten patients experiences at least one adverse event over a course of treatment, though the vast majority of those events are mild and self-limiting.1PubMed Central. Acupuncture-related adverse events: systematic review and meta-analyses of prospective clinical studies Serious complications do happen, but they are rare enough that many practitioners go entire careers without seeing one. The gap between “generally safe” and “nothing can go wrong” is where the important details live.
How Common Are Problems, and How Serious?
The best overall picture comes from pooled data across multiple clinical studies. When researchers combined results from 11 prospective trials, the rate of at least one adverse event per patient across a treatment series was about 9%, and the per-treatment rate was roughly 8%. But the serious adverse event rate was far lower: about 1 per 10,000 patients and about 8 per million individual treatments.1PubMed Central. Acupuncture-related adverse events: systematic review and meta-analyses of prospective clinical studies To put that in context, a National Institutes of Health consensus statement concluded that acupuncture has fewer side effects than many standard pharmaceutical options for pain management.2Orthopedic Reviews. Acupuncture as Part of Multimodal Analgesia for Chronic Pain
Still, “rare” is not “impossible,” and some adverse events require emergency treatment. A review of reports to the UK’s National Patient Safety Agency found the breakdown of reported incidents included retained needles (about a third of reports), dizziness (about 30%), loss of consciousness (about 19%), and pneumothorax (about 1%).3PubMed. Patient safety incidents from acupuncture treatments: a review of reports to the National Patient Safety Agency These numbers reflect what gets reported rather than what happens in routine clinical practice, so they skew toward the more dramatic end. But they map out what can go wrong when it does.
The Common, Mild Side Effects
The most frequently reported adverse events are things you would expect from being stuck with a needle. Needle pain ranges widely in studies, from about 1% to 45% of treatments, depending on how it is measured and what counts. Tiredness after a session shows up in roughly 2% to 41% of patients. Minor bleeding at needle sites occurs in anywhere from a tiny fraction to about 38% of treatments.4The American Journal of Medicine. Prospective studies of the safety of acupuncture: a systematic review That enormous range reflects different study designs and different definitions of “bleeding,” but the point is that a small spot of blood on a cotton ball is normal and expected. None of these reactions require medical attention.
Many patients also report feeling deeply relaxed during or after treatment. In one systematic review, as many as 86% of patients noted relaxation as an effect.4The American Journal of Medicine. Prospective studies of the safety of acupuncture: a systematic review This is generally considered desirable, but it means you should probably not schedule a session right before driving a long distance or doing something that requires sharp focus.
Fainting and Vasovagal Responses
Some people feel lightheaded, nauseated, or sweaty during acupuncture, and a small number actually faint. This is called a vasovagal response, and it happens when your nervous system overreacts to a stimulus by suddenly dropping your heart rate and blood pressure, temporarily reducing blood flow to the brain. These episodes occur in roughly 0.02% to 7% of treatments, a wide range that depends on the clinic, patient population, and how aggressively the practitioner needles.5PubMed Central. Acupuncture-Associated Vasovagal Response: Revised Terminology and Hospital Experience
Vasovagal episodes are not unique to acupuncture; the same thing happens to people getting blood draws or even watching a medical procedure. The triggers tend to be predictable: anxiety, an empty stomach, dehydration, or being seated upright during needling. A protocol developed at the University of Minnesota uses the acronym PEACHES (position, experience, anxiety, constitution, hydration, environment, symptom recognition) to help practitioners prevent these reactions before they happen. Patients typically recover quickly once they lie flat and have the needles removed. If you have fainted during blood draws or injections in the past, telling your acupuncturist beforehand lets them adjust their approach.
Pneumothorax: The Most Talked-About Serious Risk
A collapsed lung, or pneumothorax, is the serious complication that draws the most attention in acupuncture safety discussions, and for good reason. It is the most frequent severe adverse event tied to acupuncture needling near the chest and upper back.6Journal of Acupuncture and Meridian Studies. Using Ultrasonography Measurements to Determine the Depth of the GB 21 Acupoint to Prevent Pneumothorax The risk is concentrated at a specific acupuncture point called GB21, located on the trapezius muscle between the neck and shoulder, which is commonly needled for neck pain and muscle spasms. One review found that this single point was associated with up to 64% of acupuncture-induced pneumothorax cases.7PubMed Central. Traumatic Pneumothorax in a 58-Year-Old Man: A Case Report of a Rare Post-Acupuncture Adverse Event
The underlying issue is anatomy. At GB21, only a relatively thin layer of muscle and tissue separates the skin from the membrane lining the lungs. How thin depends on the individual. Researchers using ultrasound found that the safe needling depth at this point varies significantly between men and women, between sitting and lying positions, and between breathing in versus breathing out.8PubMed Central. Change of Safe Needling Depth at Acupoint GB21 according to Posture and Breathing Body weight matters too, but not in a straightforward way: some people with higher body weight still had very shallow safe depths because their muscle mass was low. If a practitioner uses the same insertion depth for every patient without adjusting for individual anatomy, the risk goes up for people who happen to have less tissue between skin and lung.7PubMed Central. Traumatic Pneumothorax in a 58-Year-Old Man: A Case Report of a Rare Post-Acupuncture Adverse Event
In absolute terms, pneumothorax remains rare. One large systematic review found only two cases in nearly a quarter of a million treatments.4The American Journal of Medicine. Prospective studies of the safety of acupuncture: a systematic review But it is an emergency when it happens, requiring hospital treatment and sometimes a chest tube. Symptoms usually appear within hours of a session: sudden shortness of breath, sharp chest pain that worsens when you inhale, and sometimes a dry cough. If you experience any of these after acupuncture near your upper back, shoulders, or chest, go to an emergency room and mention the treatment.
Infection
Infection from acupuncture has shifted dramatically over the decades. Earlier reviews found hepatitis transmission via reusable needles as the primary infectious risk. That has been largely eliminated by the adoption of single-use, pre-sterilized disposable needles. In more recent case-report reviews, infections were still the most common serious complication, but the source had changed: most were bacterial skin infections caused by contamination at the needle site rather than needle reuse.9PubMed Central. Adverse Events of Acupuncture: A Systematic Review of Case Reports
The bacteria involved are mostly organisms that live on normal skin. A study tracking infectious complications in acupuncture patients identified Staphylococcus as the most common culprit, followed by Streptococcus, Mycobacterium, and various other bacteria.10PubMed Central. Infectious Adverse Events Following Acupuncture: Clinical Progress and Microbiological Etiology These infections are typically localized and treatable with antibiotics, though Mycobacterium infections can be more stubborn and harder to diagnose. The risk is almost entirely tied to poor hygiene technique. If your practitioner uses sealed, single-use needles, washes their hands, and swabs the skin with alcohol before insertion, the infection risk is minimal. If you notice redness, swelling, warmth, or pus at a needle site in the days following treatment, see a doctor promptly.
Bleeding Risk for People on Blood Thinners
Patients taking anticoagulants like warfarin or direct oral anticoagulants often worry about whether acupuncture will cause dangerous bleeding. The evidence is reassuring, though not without caveats. A systematic review focusing on acupuncture in anticoagulated patients found no serious adverse events related to acupuncture and concluded that it was safe even for people with elevated clotting times.11PubMed Central. Does acupuncture increase the risk of bleeding in patients taking warfarin? In another systematic review, only one moderate bleeding event, a hip hematoma, occurred in nearly 4,000 treatments of anticoagulated patients.12PubMed Central. Acupuncture Safety in Patients Receiving Anticoagulants: A Systematic Review
A larger case-control study using real-world clinical data offered a more granular picture. Minor bleeding occurred at a rate of about 8 per 10,000 needles overall, and major bleeding was much rarer at about 4 per 100,000 needles. Anticoagulants did increase the odds of minor bleeding, but the increase in major bleeding risk was not statistically significant.13Complementary Therapies in Medicine. Bleeding risk after acupuncture in patients taking anticoagulant drugs: A case control study based on real-world data Among individual drugs, warfarin carried the highest additional risk, followed by heparin and direct oral anticoagulants. The practical takeaway: if you are on blood thinners, acupuncture is not off the table, but you should tell your practitioner so they can use thinner needles, avoid deep insertion near major vessels, and apply extra pressure after needle removal.
Broken and Retained Needles
Modern acupuncture needles are manufactured to tight standards and very rarely break during normal use. When needle fragments do end up lodged in tissue, it almost always involves older-style needles, manufacturing defects, or self-acupuncture gone wrong. One case report described a patient who broke a needle while performing self-acupuncture, and the fragment migrated to the cervical spinal canal, requiring surgical removal in a hybrid operating room.14Trauma & Case Reports. Removal of a migrated acupuncture needle from the cervical spinal canal with removal confirmation by cone-beam computed tomography in a hybrid operating room A retrospective review of spinal cord and brain injuries from embedded acupuncture needles found that self-acupuncture accounted for about a fifth of the cases, and that symptoms often did not appear until more than a month after the incident.
In most cases, retained needle fragments sit in soft tissue indefinitely without causing problems. They occasionally migrate, especially in patients with little body fat, and have been documented traveling to organs like the liver, pancreas, and kidney without producing symptoms. Complications when they do arise include localized granulomas and contact dermatitis.15PubMed Central. Permanently Retained Acupuncture Needles: Radiographic Findings and Case Report This is not something to lose sleep over with a licensed practitioner using modern needles, but it is a good reason to never attempt acupuncture on yourself.
Nerve Injury
Nerve damage from acupuncture is one of the harder complications to study because it ranges from a brief electric-jolt sensation during needling, which is common and usually harmless, to genuine mechanical injury that causes lasting numbness, weakness, or pain. The invasive nature of the procedure means nerve injury is always a theoretical possibility, particularly at points where nerves run close to the surface.16Complementary Therapies in Medicine. Incidence of nerve injury following acupuncture treatments in Taiwan In practice, clinically significant nerve injuries appear to be quite rare in the published literature and tend to involve points in the wrist, elbow, or lower leg where major nerve trunks are relatively exposed.
If you feel a shooting or electric sensation during needling, tell your practitioner immediately. A brief zap that resolves in seconds is usually just the needle brushing a nerve and is not dangerous. But persistent tingling, numbness, or weakness in a limb after a session, especially if it lasts more than a day, warrants a medical evaluation.
Electroacupuncture and Pacemakers
Standard acupuncture uses manual needles alone, but some practitioners also use electroacupuncture, which passes a small electrical current through the needles. This variant carries its own specific risks. Published reports have raised concerns that electroacupuncture could interfere with pacemakers and implantable cardioverter-defibrillators, and published guidance generally advises against using it in patients who have these devices.17PubMed. Electroacupuncture on a patient with pacemaker: a case report
A systematic review of electroacupuncture-specific adverse events identified a handful of additional risks beyond those associated with manual needling: skin pigmentation at needle sites, electrical burns, involuntary muscle spasm, implantable defibrillator shocks, and cardiac emergencies.18PubMed. Adverse events related to electroacupuncture: a systematic review of single case studies and case series If you have any implanted electrical device, make sure your practitioner knows before treatment begins. Manual acupuncture remains an option in most cases; electroacupuncture does not.
Moxibustion and Cupping
Acupuncture clinics frequently offer adjunctive therapies like moxibustion (burning dried mugwort near or on the skin) and cupping (placing suction cups on the skin). These carry their own risk profiles that patients sometimes overlook because the focus is on needles. Moxibustion involves open flame or smoldering material and predictably causes burns when not carefully managed. A systematic review of moxibustion case reports cataloged adverse events including burns, allergic reactions, infections, nausea, hyperpigmentation, and in extreme cases more serious outcomes.19PubMed Central. Safety of moxibustion: a systematic review of case reports Cupping can cause a characteristic heat-related skin pattern called erythema ab igne, as well as dermal scarring.20PubMed. Erythema ab igne and dermal scarring caused by cupping and moxibustion treatment
The circular bruise marks cupping leaves are well known and generally harmless, fading within days to a couple of weeks. But thermal injuries and scarring are a different matter. If your practitioner suggests moxibustion, ask about their burn-prevention protocol and whether they use indirect moxibustion (where the herb does not directly contact skin), which carries a lower burn risk.
Acupuncture During Pregnancy
Traditional acupuncture training designates certain points as “forbidden” during pregnancy, based on the belief that stimulating them could induce labor or miscarriage. The scientific evidence, however, does not support this concern. A review of 15 clinical trials covering more than 800 women who received thousands of treatments at one or more forbidden points found rates of preterm birth and stillbirth equivalent to those in untreated control groups and consistent with background rates in the general population. Observational data from a large cohort of nearly 5,900 pregnant women needled at forbidden points at all stages of pregnancy showed similar results, and laboratory experiments in pregnant rats also failed to produce miscarriage or fetal loss.21PubMed Central. The safety of obstetric acupuncture: forbidden points revisited
That said, the overall quality of the evidence remains limited, and at least one systematic review concluded that the strength of evidence was insufficient to confidently recommend using forbidden points before 37 weeks of pregnancy.22PubMed Central. Using Forbidden Points in Pregnancy: Adverse Outcomes and Quality of Evidence in Randomized Controlled Trials—A Systematic Narrative Review In practice, many acupuncturists avoid these points before the final weeks of pregnancy as a precaution, even though the data so far has not shown harm. If you are pregnant, seek a practitioner experienced in obstetric acupuncture and discuss the approach to point selection.
Acupuncture in Children and Cancer Patients
Two populations often assumed to be too fragile for acupuncture are children and people undergoing cancer treatment. The evidence on both is more encouraging than you might expect, though the data is thin. A retrospective study of acupuncture in a pediatric cancer unit tracked over 1,100 sessions, including more than 9,300 semi-permanent needles and 5,100 filiform needles used on children, many of whom had dangerously low white blood cell or platelet counts. Despite performing a third of sessions in children with neutropenia and over a quarter in children with thrombocytopenia, the study found no cases of sepsis, local infection, or skin irritation. The single adverse event was a superficial ear hematoma in a child with very low platelets, which resolved on its own.23PubMed Central. Safety of Acupuncture Using Semi-Permanent Needles in a Pediatric Cancer Unit: A Retrospective Study
For adult cancer patients, expert consensus guidelines recommend a system of “red and amber flags” that highlight specific clinical situations where urgent referral is needed or where needling should be modified.24PubMed Central. Acupuncture in cancer care: recommendations for safe practice (peer-reviewed expert opinion) Low platelet counts, active infections, skin lesions at needle sites, and areas affected by lymphedema all require special attention. The general message from the oncology acupuncture literature is that acupuncture can be done safely in these patients, but only when the practitioner understands the specific risks that cancer and its treatment create.
Allergic and Skin Reactions
Acupuncture needles are typically made of stainless steel, which contains trace amounts of nickel and chromium. People with known nickel sensitivity can develop contact dermatitis at needle sites, a reaction that was identified in the medical literature as far back as the 1970s. Modern needles are sometimes coated with silicone for smoother insertion, and rare allergic reactions to these coatings have also been reported. If you have a known metal allergy, mention it before treatment. Some manufacturers produce needles with alternative coatings or compositions that may be suitable for sensitive patients.
How to Reduce Your Risk
Most serious acupuncture complications trace back to either inadequate training or poor hygiene, both of which are preventable through regulation and patient awareness. A recent review of safety-improvement strategies in acupuncture practice emphasized mandatory accreditation and licensing, sterilized single-use needles, regular equipment checks, and ongoing education for practitioners.25PubMed Central. How to Improve Safety in Acupuncture Clinical Practice? In the United States, most states require licensure and a clean-needle certification for acupuncturists, but the specifics vary, and in a few states acupuncture is essentially unregulated. Checking that your practitioner holds a current state license and has completed a certified training program is the single most effective thing you can do to protect yourself.
Beyond credentials, a few practical steps lower your risk further:
- Disclose everything: Tell your practitioner about blood thinners, implanted devices, pregnancy, metal allergies, bleeding disorders, and any history of fainting during medical procedures.
- Watch the needles: Your practitioner should open sealed, individually packaged needles in front of you. If you see needles taken from a container or jar, ask about sterilization.
- Eat and hydrate beforehand: Showing up on an empty stomach increases the chance of a vasovagal episode.
- Know the warning signs: Sudden chest pain or shortness of breath after a session that included upper-back or shoulder points warrants an emergency room visit. Persistent numbness or weakness in a limb after treatment should prompt a call to your doctor. Redness, warmth, or swelling at a needle site days later may be an infection.
Acupuncture complications that make it into case reports tend to cluster in a few scenarios: unlicensed practitioners working outside regulated settings, self-acupuncture, or treatment at anatomically risky points without proper depth adjustment. The evidence suggests that when Clean Needle Technique guidelines are followed and the practitioner is properly trained, the rate of anything going seriously wrong is very low.9PubMed Central. Adverse Events of Acupuncture: A Systematic Review of Case Reports That is not zero, and it is worth knowing what the risks are. But for most people, acupuncture sits firmly on the safer end of the spectrum when compared with the drugs and procedures it is often used alongside.