What Are the Side Effects of Radiofrequency Ablation?

Radiofrequency ablation (RFA) uses heat generated by high-frequency electrical current to destroy targeted tissue, and its side effects range from mild post-procedure soreness and fatigue to rare but serious complications like organ perforation or infection. The specific risks depend heavily on where in the body the procedure is performed: cardiac ablation for arrhythmias, tumor ablation in the liver or lungs, nerve ablation for chronic pain, and thyroid nodule treatment each carry their own profiles. Most people experience some combination of discomfort, low-grade fever, and fatigue in the days following the procedure, but severe outcomes are uncommon.

Post-Ablation Syndrome and the First Few Days

The most universal side effect of RFA, regardless of where it is applied, is a cluster of symptoms collectively called post-ablation syndrome. In a prospective study of patients undergoing percutaneous RFA, about 81% developed flu-like symptoms and 42% had low-grade fever afterward. Symptoms peaked around day three and mostly resolved by day ten. Roughly a third of patients experienced the full syndrome of both fever and flu-like malaise together.¹ Pain at the treatment site is also common. In a study of pediatric patients with solid tumors, post-procedure pain was moderate (a median of 5 out of 10) and lasted a median of nine days.²

This constellation of fever, fatigue, and achiness is essentially the body’s inflammatory response to the tissue that was just destroyed. It is not a sign that something went wrong. Doctors expect it and typically manage it with over-the-counter pain relievers and rest. The severity tends to scale with the volume of tissue ablated: a small thyroid nodule procedure will usually produce milder symptoms than ablation of a large liver tumor.

Skin Burns at the Grounding Pad

RFA works by passing electrical current through the body between a needle electrode and one or more grounding pads placed on the skin. The pads themselves can heat up enough to cause burns, and this risk has grown as generators have become more powerful. The rate of severe (second- or third-degree) skin burns ranges from about 0.1% to 3.2% across studies, while milder first-degree burns occur in 5% to 33% of cases.³ Techniques like sequentially activating multiple grounding pads have been developed to spread the current and reduce heating at any single pad site.⁴

If you are having an RFA procedure, you may notice redness or tenderness where the pads were placed. Mention it to your care team, but a mild pink mark that fades within a day or two is within the expected range. A blister or deeper wound is not, and should be evaluated.

Side Effects of Cardiac Ablation

Cardiac RFA is most commonly used to treat atrial fibrillation and other heart rhythm disorders. Because the procedure involves threading catheters through blood vessels into the heart, it carries a distinct set of risks that have nothing to do with the radiofrequency energy itself.

Vascular Access Problems

The catheters typically enter through large veins in the groin. Complications at these access sites include pseudoaneurysms (a kind of contained blood vessel leak), arteriovenous fistulas (abnormal connections between an artery and vein), and hematomas. In one study, about 1.6% of patients had a major femoral vascular complication, with pseudoaneurysms and fistulas accounting for most of them.⁵ These sometimes require readmission after discharge but are generally treatable.

Cardiac Tamponade

The most feared acute complication of cardiac ablation is cardiac tamponade, where fluid (usually blood) accumulates in the sac surrounding the heart and compresses it. This is the leading cause of procedure-related death in atrial fibrillation ablation, though it remains uncommon. In a large analysis of over 32,000 procedures, tamponade occurred in about 0.9% of cases. Women faced roughly double the odds compared with men.⁶ When tamponade does happen, it requires emergency drainage of the fluid, and in severe cases surgical repair. One reported case involved perforation of the left atrial appendage that necessitated open-chest surgery.⁷

Atrio-Esophageal Fistula

This is the rarest and most dangerous complication of atrial fibrillation ablation. Because the esophagus runs directly behind the left atrium, the heat from ablation can injure the esophageal wall and, over days to weeks, create an abnormal connection between the heart and the esophagus. Patients tend to present about 10 to 16 days after the procedure with vague symptoms like fever and neurological abnormalities that can mimic stroke or sepsis.⁸ In one early case series, all patients died, and only a minority received the correct diagnosis before death. This complication is extremely rare but has a high mortality rate, driven by cerebral air embolism, massive bleeding, or septic shock.⁹ Awareness of the diagnosis has improved since those early reports, and modern centers use esophageal temperature monitoring and other protective strategies during the procedure.

Nerve Injury and Silent Cerebral Events

The phrenic nerve, which controls the diaphragm, runs close to areas targeted during cardiac ablation. Damage to it can cause diaphragm paralysis. At least one case of permanent right diaphragm paralysis has been documented following RFA for inappropriate sinus tachycardia.¹⁰

Perhaps more unsettling is the finding that cardiac ablation can cause tiny blood clots or gas bubbles to travel to the brain, producing what are called silent cerebral lesions. In one study, post-procedure brain MRI detected new embolic lesions in about 14% of patients, even though most had no obvious neurological symptoms.¹¹ A separate pilot study found a somewhat lower rate of around 5% to 7.5%, depending on the catheter design used.¹² The long-term significance of these tiny lesions is still being studied, but their presence has pushed the field toward anticoagulation protocols and newer catheter designs that aim to reduce embolism risk.

Lung Tumor Ablation and Pneumothorax

When RFA is used to treat lung tumors, the needle must pass through the chest wall and lung tissue to reach the target. This makes pneumothorax (a collapsed or partially collapsed lung from air leaking into the chest cavity) the dominant complication. Reported rates vary widely depending on study methods: one study found pneumothorax in about 52% of treatment sessions, with about 21% of those cases requiring a chest tube for drainage.¹³ Another reported a lower rate of about 11% detected on imaging.¹⁴ The discrepancy likely reflects differences in detection sensitivity and patient populations. Pleural effusion, a buildup of fluid around the lung, occurred in roughly 19% of sessions in the larger study. Most pneumothoraces are small and resolve on their own; only a subset are large enough to need intervention.

Risk factors include the tumor’s location deeper within the lung, the number of needle passes, and underlying lung disease like emphysema. If you are having lung RFA, expect to be monitored closely for breathing difficulty in the hours after the procedure.

Liver Ablation Risks

RFA is a workhorse treatment for liver tumors, particularly hepatocellular carcinoma and certain metastases. The liver’s rich blood supply and close proximity to bile ducts, bowel, and the diaphragm create several potential complications beyond the general post-ablation syndrome.

Bile Duct Injury

Heat from the ablation can damage nearby bile ducts. In a study of 571 liver RFA sessions, bile duct changes showed up on imaging in about 12% of sessions and 17% of patients. Most of these changes were minor upstream dilation of ducts near the ablation zone and required no treatment. Only one patient developed cholangitis (a bile duct infection) that needed specific management.¹⁵ So while the imaging findings are common, clinically meaningful problems are rare.

Liver Abscess

Infection of the ablated tissue is perhaps the most clinically significant complication specific to liver RFA. The dead tissue left behind by ablation can become a breeding ground for bacteria, particularly in patients who have prior biliary procedures or abnormalities. In a study of 751 ablation procedures, liver abscess developed after about 1.7% of sessions. Key risk factors included pre-existing biliary abnormalities and prior transcatheter arterial chemoembolization. All affected patients recovered with antibiotics and drainage.¹⁶ Patients with a history of enterobiliary anastomosis (a surgical connection between the intestine and bile duct) are at elevated risk, as this connection provides a direct route for gut bacteria to reach the liver.¹⁷

The tricky part is diagnosis. Air within the ablation zone is a normal post-procedure finding on imaging, which makes it hard to distinguish expected post-ablative necrosis from an actual abscess. New or worsening fever, chills, or increasing pain days to weeks after liver RFA should prompt imaging and blood work.¹⁸

Spine and Pain Management Ablation

RFA of the medial branch nerves supplying spinal facet joints is one of the most common pain management procedures performed worldwide. Compared with tumor or cardiac ablation, the risks are generally lower because the target structures are smaller and more superficial. Still, side effects do occur.

The most typical complaint is a temporary increase in pain, sometimes called a “pain flare,” at the treatment site. One comparative study found a 7% complication rate with radiofrequency medial branch neurotomy, primarily consisting of transient pain flares and minor motor deficits.¹⁹ Numbness or unusual sensations (paresthesias) can also develop. A case report described a patient who experienced pain, numbness, and swelling on the buttock and thigh after lumbar medial branch RFA, with allodynia (pain from normally painless touch) over the affected area. After the opposite side was treated, similar symptoms appeared on that side as well. Both episodes resolved over time.²⁰

These nerve-related side effects are generally transient, but they can be alarming when they appear, especially if nobody warned you about them beforehand. Muscle weakness in the area served by the treated nerve is possible but uncommon and usually mild.

Thyroid Nodule Ablation and Voice Changes

RFA has become an increasingly popular alternative to surgery for benign thyroid nodules. The most concerning side effect unique to this application is vocal fold immobility, because the recurrent laryngeal nerve runs right alongside the thyroid gland. In a survey of laryngologists, one-third of respondents reported having seen vocal fold immobility after thermal ablation of thyroid nodules, with 81% of those cases documented on laryngeal examination.²¹ This does not mean a third of patients experience it; rather, the finding highlights that voice changes are a recognized complication that clinicians encounter with some regularity. Most cases are temporary, but the risk underscores why voice assessment before and after the procedure is recommended.

Other side effects of thyroid RFA include neck pain, swelling, skin burns over the treatment site, and hematoma formation. These are typically self-limiting.

RFA for Barrett’s Esophagus

RFA is used to destroy precancerous tissue in the esophagus caused by Barrett’s esophagus. The side-effect profile here is quite different from tumor ablation. Chest discomfort is the most common complaint but is usually mild and short-lived. Esophageal strictures (narrowing from scar tissue) can develop, though they generally respond well to dilation. Significant bleeding is rare.²² Difficulty swallowing for a few days after the procedure is common and expected as the treated tissue heals.

Kidney Tumor Ablation

For small kidney tumors, percutaneous RFA offers a less invasive option than surgery. The complication profile includes hemorrhage around the kidney, injury to the ureter or the junction where the kidney meets the ureter, infection or abscess, sensory or motor nerve injury, pneumothorax (when the approach passes near the lung base), and needle tract seeding of tumor cells.²³ Clinically significant urine leaks are very rare; in a series of 100 kidney tumor ablations, only one occurred, and it was related to downstream obstruction.²⁴

The kidney is well-perfused, which means blood flow acts as a natural heat sink and can protect surrounding structures to some degree. But it also means tumors near large blood vessels may not be completely ablated, potentially requiring retreatment.

How Pulsed Field Ablation Compares

A newer technology called pulsed field ablation (PFA) has entered clinical use, particularly for cardiac arrhythmias, and part of its appeal is a potentially different safety profile. PFA uses brief, intense electrical pulses to destroy cells without generating the sustained heat that causes thermal injury to nearby structures. In a preclinical comparison for heart ablation, steam pops and ventricular fibrillation occurred in 4 of 12 radiofrequency ablations but none of 12 pulsed field ablations.²⁵

In a clinical comparison for atrial fibrillation, overall complication rates were about 3.4% with PFA, 5.5% with radiofrequency, and 8.6% with cryoballoon ablation. The difference was statistically significant between PFA and cryoballoon, with transient phrenic nerve injury (at about 4.8%) being the main driver of higher cryoballoon complications. Major complication rates were similar across all three approaches.²⁶ PFA is not risk-free, though: it has been associated with transient coronary artery spasm and hemolysis (destruction of red blood cells) in some reports. The technology is still maturing, and head-to-head data with radiofrequency will accumulate over the coming years.

Who Faces Higher Risk

Certain patient factors shift the odds of complications. For cardiac ablation, women face roughly twice the risk of cardiac tamponade compared with men, possibly due to thinner atrial walls.⁶ For liver ablation, patients with pre-existing biliary abnormalities or a history of bile duct surgery face elevated abscess risk.¹⁶ For lung ablation, emphysema and deep tumor location increase the chance of pneumothorax. The size and number of lesions being treated also matter across all applications: more tissue ablated generally means more inflammation and a higher chance that nearby structures get caught in the heat zone.

Operator experience is another real factor. Many complications of RFA are technique-dependent, from how the grounding pads are placed to how aggressively the ablation is pursued near critical structures. Thermal protection strategies, including injecting fluid to displace vulnerable tissues away from the ablation zone, are standard practice at experienced centers and can meaningfully reduce collateral damage. If you are considering an RFA procedure, the volume and track record of the facility performing it is worth asking about.