Supplemental oxygen is a common and often necessary treatment, but it does come with side effects ranging from mild nasal dryness to, in rare cases, serious lung or tissue damage. Most people on standard home oxygen experience only minor discomfort that can be managed with simple adjustments. The more serious complications tend to occur at higher concentrations or pressures, or in specific vulnerable populations like premature infants or people with COPD.
Nasal Dryness, Nosebleeds, and Irritation
The most common complaint from people using a nasal cannula is dryness in the nose and throat. Oxygen delivered through tubing doesn’t carry the same moisture as normal air, and over time this strips moisture from your nasal lining. The result is a dry, irritated nose that can crack, crust over, or bleed. Some people also develop a sore throat, especially overnight.
Beyond dryness, the physical tubing itself causes problems. Nasal cannulas rest on the ears, upper lip, and cheeks for hours at a time, and face masks press against the bridge of the nose. The bridge of the nose is the single most common site for skin breakdown because there’s very little cushioning tissue between skin and bone. In studies of patients wearing oxygen masks, nearly half developed some form of facial pressure sore, with the vast majority occurring on the nasal bridge.
British Thoracic Society guidelines recommend humidification when oxygen flows above 4 liters per minute. Below that, most people tolerate dry oxygen without major issues, though some still notice discomfort. If you’re on higher flows, a humidifier bottle attached to your oxygen source makes a significant difference. For skin irritation, protective dressings like hydrocolloid pads or transparent film over pressure points can prevent sores from forming in the first place.
Carbon Dioxide Buildup in COPD Patients
If you have COPD or another chronic lung condition, too much supplemental oxygen can cause a dangerous rise in carbon dioxide levels in your blood. This is called oxygen-induced hypercapnia, and it happens through several overlapping mechanisms. Normally, low oxygen levels act as a breathing signal for people with severe COPD. When supplemental oxygen raises those levels too high, the signal weakens and breathing slows. At the same time, oxygen changes how blood flows through the lungs and how efficiently hemoglobin releases carbon dioxide, further allowing CO2 to accumulate.
Symptoms of carbon dioxide buildup include drowsiness, confusion, headaches, and in severe cases, loss of consciousness. This is why people with COPD are typically prescribed specific, carefully controlled oxygen flow rates rather than being told to turn the dial up whenever they feel short of breath. If you have COPD and notice increasing sleepiness or confusion while using oxygen, that’s worth immediate attention.
Lung Damage From High Oxygen Concentrations
Breathing oxygen at concentrations well above normal (close to 100%) can directly injure lung tissue. This type of damage, known as pulmonary oxygen toxicity, occurs because high oxygen levels generate reactive molecules that attack cell membranes in the airways and air sacs. Prolonged exposure can destroy the protective lining of the lungs, cause fluid buildup, and eventually lead to scarring and collapse of air sacs.
Symptoms can appear within 24 hours of breathing pure oxygen and typically start mild: a tickling or light burning sensation when you inhale, followed by chest tightness, coughing, and difficulty breathing. In most patients, these symptoms fade within about four hours after oxygen levels are reduced. This type of toxicity is not a concern for people on standard home oxygen at low flow rates. It becomes relevant in hospital settings where patients receive high-concentration oxygen through ventilators or during certain medical procedures.
Absorption Atelectasis
High-concentration oxygen can also cause small sections of the lung to collapse through a process called absorption atelectasis. Normally, the nitrogen in air helps keep tiny air sacs (alveoli) inflated because it doesn’t get absorbed into the blood very quickly. When you breathe mostly oxygen, that nitrogen is replaced. Oxygen gets absorbed into the bloodstream much faster, and without the nitrogen scaffolding, the air sacs can deflate and close off. This reduces the lung’s ability to exchange gases and can worsen breathing difficulty, which is the opposite of what the oxygen was meant to do.
Nervous System Effects at High Pressures
Central nervous system toxicity is almost exclusively a concern during hyperbaric oxygen therapy, where oxygen is delivered at pressures several times higher than normal atmospheric pressure. At those pressures, oxygen can trigger seizures. Early warning signs include muscle twitching (particularly around the mouth and hands), facial paleness, nausea, dizziness, and jerky breathing patterns. If exposure continues, the twitching progresses to full convulsions that the person typically has no memory of afterward. Factors like fatigue, stress, cold temperatures, and elevated carbon dioxide levels make seizures more likely.
This side effect does not apply to standard home oxygen use or even most hospital oxygen therapy. It’s specific to pressurized environments used in specialized treatments.
Risks for Premature Infants
Premature babies are uniquely vulnerable to supplemental oxygen because their eyes are still developing. Too much oxygen in the first weeks of life triggers a condition called retinopathy of prematurity, where the blood vessels in the retina stop growing normally and then overgrow in a chaotic way that can lead to vision loss or blindness. Excessive oxygen has been recognized as a major risk factor for this condition for over 50 years.
The process unfolds in two phases. First, high oxygen levels shut down normal blood vessel growth in the retina during the earliest weeks after birth. Then, as the retina continues to develop and demand more blood supply, the lack of adequate vessels creates oxygen starvation, which triggers abnormal vessel growth that can pull on the retina and cause detachment. To manage this risk, neonatal units carefully target oxygen saturation ranges: 90 to 94% for infants under 32 weeks of age, and 92 to 98% for older newborns. Studies have found that keeping oxygen levels in the lower range during those critical first weeks cuts the risk of severe retinopathy roughly in half.
Fire and Safety Hazards
Oxygen itself doesn’t burn, but it makes everything around it burn faster and hotter. This creates a real fire risk in the home. In the United States, home oxygen equipment is involved in roughly 1,190 burn injuries treated in emergency rooms each year. Fire departments respond to about 182 home fires annually where oxygen equipment is directly involved, and an average of 46 people die in those fires each year.
Smoking is by far the leading cause. In UK data tracking serious incidents with home oxygen, smoking was associated with the majority of fatal and hospitalization-level events. Among non-smoking-related fires, gas stoves, candles, lighters, and electric heaters were the most common ignition sources. Keeping oxygen equipment at least 10 feet from open flames, never smoking while using oxygen, and avoiding petroleum-based products (like certain lip balms) on your face while wearing a cannula are the most important precautions.
Managing Common Side Effects
Most people on long-term home oxygen deal primarily with dryness and skin irritation, both of which respond well to straightforward measures. A humidifier bottle on your oxygen concentrator or tank adds moisture to the air before it reaches your nose. Water-based nasal sprays or gels (not petroleum jelly, which is a fire risk near oxygen) can keep nasal passages from cracking and bleeding. Rotating your cannula position slightly, using soft ear pads on the tubing, and applying protective film or foam dressings to the nose bridge can prevent the skin sores that develop from constant contact.
If you notice increasing headaches, confusion, or excessive sleepiness while on oxygen, particularly if you have a lung condition like COPD, those symptoms suggest your carbon dioxide levels may be climbing and your flow rate may need adjustment. Persistent nosebleeds, especially if accompanied by crusting, pain, or difficulty breathing through the nose, also warrant a conversation about humidity settings or alternative delivery methods.