Mohs surgery is performed under local anesthesia in the vast majority of cases, not general anesthesia. You stay fully awake throughout the procedure, sitting or lying in what looks more like an exam room than an operating theater. The surgeon numbs the treatment area with an injectable anesthetic, removes thin layers of skin cancer one at a time, and checks each layer under a microscope while you wait. General anesthesia is reserved for uncommon situations, and understanding when and why those exceptions arise helps ease one of the most common anxieties people have before the procedure.
Why Local Anesthesia Is the Standard
Mohs micrographic surgery was developed in the 1930s by Dr. Frederic E. Mohs, originally as a technique called chemosurgery that used zinc chloride paste applied to the skin.1PubMed. History of Mohs surgery The modern version, known as the fresh tissue technique, evolved into an outpatient procedure done in a dermatologist’s office. The entire design of Mohs surgery depends on the patient being awake and comfortable rather than under deep sedation. Here is why:
The procedure works in stages. The surgeon injects local anesthetic around the tumor site, removes a thin layer of tissue, and then maps and examines it under a microscope. If cancer cells are found at any edge, the surgeon goes back and removes another thin layer from only that specific area. Each cycle can take 30 to 90 minutes, including lab processing time. A straightforward case might require one or two stages, but more complex cancers can take four or more. Between stages, you sit in a waiting area, read, eat a snack, or scroll through your phone. General anesthesia would make this iterative, stop-and-start workflow impractical and would expose you to far more medical risk than the procedure warrants.
Local anesthesia also gives the surgeon real-time feedback. If you feel a sharp sensation during tissue removal, that tells the surgeon something about the depth and proximity of nerves. And because you are alert, the surgeon can reposition you easily, communicate about what they are seeing, and adjust their approach without the time pressure that general anesthesia imposes.
What the Numbing Injection Involves
The local anesthetic most commonly used is lidocaine, often mixed with epinephrine. The lidocaine blocks nerve signals so you cannot feel pain, and the epinephrine constricts nearby blood vessels, which reduces bleeding and helps the lidocaine last longer at the site.2Dermatologic Surgery. Incidence of Epinephrine Reactions With Local Anesthesia in Mohs Micrographic Surgery This is the same type of injection you would get at the dentist, applied to skin instead of gums.
The initial needle stick and the pressure of the fluid entering the tissue are the most uncomfortable parts. Most people describe a brief burning sensation lasting a few seconds, followed by complete numbness in the area. For subsequent stages, the surgeon reinjects, though the area is often still partially numb from the prior round, so the discomfort tends to decrease as the procedure goes on.
A prospective study measuring blood levels of lidocaine during Mohs surgery found that even after multiple rounds of injections, the highest peak serum lidocaine concentration detected in any patient was 0.3 micrograms per milliliter, with the average falling below 0.1 micrograms per milliliter and essentially undetectable.3Journal of the American Academy of Dermatology. Safety of peak serum lidocaine concentration after Mohs micrographic surgery: a prospective cohort study For context, toxic symptoms from lidocaine typically begin at levels above 5 micrograms per milliliter. The amounts used in Mohs surgery do not come close to that threshold, even in procedures requiring many stages.
Dealing With Anxiety Without Going Under
Being awake during surgery understandably makes some people nervous. The good news is that managing that anxiety does not require stepping up to general anesthesia. Many Mohs surgeons address pre-procedure anxiety with a mild oral sedative taken about an hour before the appointment. A randomized, placebo-controlled trial found that a single 5-milligram dose of oral diazepam provided a sustained reduction in anxiety during Mohs surgery with excellent patient safety.4PubMed. Efficacy and Safety of Anxiolytics in Mohs Micrographic Surgery: A Randomized, Double-Blinded, Placebo-Controlled Trial A survey of Mohs specialists in Australia confirmed that diazepam was the preferred and considered the safest oral option for managing perioperative anxiety in this setting.5PubMed. The use of oral benzodiazepines for patient anxiety associated with Mohs micrographic surgery: An Australian survey
If you are prescribed an anxiolytic, you will need someone to drive you home. But the medication wears off within a few hours, and you remain conscious and able to communicate throughout the procedure. This is a far cry from general anesthesia, where you are completely unconscious, intubated, and monitored by an anesthesiologist. The mild sedative simply takes the edge off while leaving you aware and cooperative.
Some offices also use non-pharmacological strategies: music through headphones, guided breathing exercises, or simply letting a companion sit with you. For the majority of patients, some combination of a calm clinical environment and local anesthesia alone is enough. The anxiolytic option exists for people who need a bit more help.
Situations Where General Anesthesia Comes Into Play
There are real, if relatively rare, circumstances where general anesthesia becomes part of a Mohs case. The most common reason has nothing to do with the tumor removal itself but rather with the reconstruction that follows it.
Mohs surgery sometimes leaves a wound that requires a complex flap or graft to close, especially on the nose, around the eyes, or near the ears. When the repair is straightforward, the Mohs surgeon typically handles the closure in the same office visit under local anesthesia. But for larger or more anatomically complicated defects, a plastic surgeon or oculoplastic surgeon may take over, and the complexity of the reconstruction can require deeper anesthesia. A review of anesthesia considerations for nasal Mohs defects noted that patients needing surgical repair after Mohs may require anesthesia “anywhere on the spectrum from local anesthesia only to general endotracheal anesthesia,” depending on the extent of the reconstruction and the patient’s medical status.6PubMed Central. A note on anesthesia for mohs nasal defects In those cases, the Mohs portion still happens under local, and the patient transitions to an operating room for the reconstructive phase.
The timing can be immediate or delayed. Sometimes a temporary dressing is placed over the Mohs wound, and the reconstruction is scheduled for a later date in a surgical suite. Other times, the plastic surgeon is available the same day and the patient is moved to a facility with anesthesia capabilities. Either way, the decision about whether general anesthesia is needed belongs to the reconstructive surgeon and the anesthesiologist, not the Mohs surgeon.
Mohs Surgery in Children
Skin cancer in children is uncommon, but when it occurs, Mohs surgery is sometimes the best option because of its tissue-sparing precision. The challenge is that young children cannot be expected to lie still for long stretches, tolerate repeated injections, or cooperate with the stop-and-go rhythm of the procedure. A systematic review of Mohs surgery in pediatric patients identified patient cooperation and concerns about the safety of prolonged general anesthesia as the most commonly cited challenges.7PubMed. Systematic review of Mohs micrographic surgery in children: Identifying challenges and practical considerations for successful application
For older children and teenagers who can understand what is happening and stay calm, local anesthesia with or without mild sedation may work well. For very young children, general anesthesia is sometimes the only realistic option, but it introduces its own concerns. The iterative nature of Mohs means the child could be under anesthesia for an extended and somewhat unpredictable amount of time. This has led some centers to modify their approach. One strategy involves performing the tumor removal in stages under brief sedation, processing the tissue while the child recovers, and returning only if another layer is needed. Other centers coordinate with pediatric anesthesiologists to manage a single, continuous anesthetic session.
The rarity of pediatric Mohs cases means there is no single dominant protocol. Each case tends to be handled individually, balancing the child’s age and temperament against the tumor’s size and location.
What About Twilight Sedation?
Between full local anesthesia and general anesthesia, there is a middle tier often called “twilight sedation” or monitored anesthesia care. This involves intravenous medications that make you drowsy and relaxed while local anesthetic still does the actual pain-blocking work. You breathe on your own, you may drift in and out of light sleep, and you typically have little memory of the procedure afterward.
Twilight sedation is common in many types of dermatologic and plastic surgery procedures, but it is unusual during standard Mohs surgery. The practical reason is straightforward: Mohs procedures take place in outpatient dermatology offices that are not equipped for IV sedation or continuous anesthesia monitoring. Moving the operation to a surgery center or hospital just to provide twilight sedation adds cost, logistical complexity, and often delays the procedure, all for a level of comfort that mild oral sedation and local anesthesia can usually provide.
That said, some patients with severe needle phobia, certain neurological conditions, or extensive tumors requiring unusually long procedures may benefit from monitored sedation. When this is the case, the Mohs portion is typically scheduled at an ambulatory surgery center rather than the dermatologist’s office.
Medical Conditions That Affect the Anesthesia Plan
Certain medical conditions can influence which anesthesia approach your surgeon recommends, though they rarely push the procedure toward general anesthesia on their own. Patients on blood thinners, for example, are generally kept on their medications during Mohs surgery because the risk of a cardiovascular event from stopping them outweighs the risk of extra bleeding. Local anesthesia with epinephrine actually helps manage bleeding in these patients.
People with pacemakers or implanted defibrillators sometimes worry about interference from surgical equipment, but standard Mohs instruments pose no risk to these devices. Electrosurgery tools used for hemostasis can theoretically interact with certain cardiac implants, but your surgeon and cardiologist can coordinate precautions in advance.
Patients with a documented allergy to lidocaine are sometimes concerned they cannot have Mohs surgery under local anesthesia at all. True lidocaine allergy is extremely rare. Most reported reactions are actually vasovagal episodes (fainting) or responses to the epinephrine component rather than the anesthetic itself. When a genuine allergy exists, alternative local anesthetics from a different chemical class can be used. The allergy almost never means you need general anesthesia.
For patients with significant movement disorders, severe dementia, or certain psychiatric conditions that prevent them from remaining still, the conversation about deeper sedation becomes more relevant. Even then, the goal is typically the lightest level of sedation that allows the surgery to proceed safely rather than jumping straight to general anesthesia.
How Long the Procedure Takes and What to Expect
One of the biggest sources of pre-procedure anxiety is uncertainty about the timeline. Most Mohs cases involve one to three stages and take somewhere between two and four hours from start to finish, including waiting time while slides are processed. You should plan for most of a morning or afternoon, but some cases wrap up in under two hours, and complex ones can stretch longer.
You arrive at the office, the surgeon marks the lesion and takes photos for the medical record, and then the local anesthetic is injected. The first layer of tissue is removed with a scalpel. A temporary bandage is placed, and you move to a waiting area while a technician processes, stains, and maps the tissue. The surgeon examines the slides. If all margins are clear of cancer cells, the wound is closed or referred for reconstruction. If cancer remains at any edge, you return to the procedure room, the area is re-numbed, and a targeted layer is removed from just that section.
You can eat before and during the procedure unless your surgeon says otherwise, which is another contrast with general anesthesia, where fasting is required. Comfortable, button-down clothing that does not need to be pulled over your head is a practical tip, especially for facial procedures. Bringing something to occupy yourself during the waiting periods also helps.
Why Surgeons Prefer to Avoid General Anesthesia
Beyond the practical logistics, there are genuine medical reasons that Mohs surgeons work hard to keep patients under local anesthesia. General anesthesia carries its own set of risks: reactions to anesthetic agents, airway complications, post-operative nausea, and the small but real possibility of serious cardiovascular events. These risks increase with age, and skin cancer patients skew older. Adding general anesthesia to a procedure that can be done safely in an office setting changes the risk-benefit calculation in the wrong direction for most patients.
There is also a cost difference. An outpatient Mohs procedure under local anesthesia avoids facility fees from hospitals or surgery centers, anesthesiologist charges, and recovery room costs. For a procedure that is already one of the more expensive dermatologic treatments, keeping it in-office makes the economics more manageable for patients and insurers alike.
Recovery is faster, too. After local anesthesia, you walk out of the office and drive yourself home (unless you took an anxiolytic). After general anesthesia, you need supervised recovery time, a driver, and often feel groggy or nauseated for the rest of the day. For a procedure where the surgical wound itself typically causes only mild discomfort managed with over-the-counter pain relievers, subjecting the patient to the recovery burden of general anesthesia is hard to justify.
Epinephrine Reactions and What They Feel Like
Because the local anesthetic used in Mohs surgery typically contains epinephrine, some patients experience brief sensations that can be alarming if unexpected. These include a racing heartbeat, a jittery feeling, slight trembling in the hands, or a sense of anxiety that comes on suddenly. These symptoms are caused by a small amount of epinephrine entering the bloodstream, not by a true allergic reaction or anything dangerous. They usually pass within a few minutes.
It helps to know this ahead of time because the sudden onset of a pounding heart mid-procedure can easily be mistaken for a panic attack or an allergic reaction, which then amplifies the anxiety. Telling your surgeon if you have experienced these symptoms before allows them to adjust the concentration of epinephrine or inject more slowly.
True allergic reactions to local anesthetics are vanishingly rare. Most adverse events during Mohs are vasovagal in nature, meaning they involve a sudden drop in blood pressure and heart rate triggered by stress, the sight of blood, or simply lying flat for too long. Vasovagal episodes are managed by elevating your legs, giving you water, and waiting a few minutes. They are unpleasant but not dangerous and do not mean you need general anesthesia for future procedures.