Neffy Side Effects: What You Need to Know

If you've been prescribed Neffy (Epinephrine nasal spray), you may be wondering what side effects to expect. Neffy is the first needle-free epinephrine option for emergency treatment of anaphylaxis, and like all medications, it can cause side effects.

The good news: most side effects are mild, temporary, and related to the nasal delivery. The important thing to remember is that Neffy is used during life-threatening allergic emergencies — the benefits of treating anaphylaxis always outweigh the risks of side effects.

What Is Neffy?

Neffy is a nasal spray that delivers Epinephrine to treat severe allergic reactions (anaphylaxis) in adults and children aged 4 and older weighing at least 33 lbs. Unlike traditional auto-injectors like EpiPen or Auvi-Q, Neffy requires no needles — just one spray into one nostril. For more details, see our complete guide on what Neffy is and how it works.

Common Side Effects

The following side effects are the most frequently reported in clinical trials. They are generally mild to moderate and resolve on their own within minutes to hours:

• Nasal discomfort — The most commonly reported side effect. You may feel a burning, stinging, or tingling sensation in your nose after using Neffy.
• Headache — A mild headache may occur after use.
• Throat irritation — Some patients report a scratchy or irritated throat.
• Chest and nasal congestion — A feeling of stuffiness in the nose or chest area.
• Feeling nervous, anxious, or overly excited — This is a normal effect of Epinephrine. Your heart may race and you may feel jittery. This is the medication working.
• Nosebleed — Minor nosebleeds can occur due to the nasal delivery.
• Nose pain — Temporary pain or pressure in the nose.
• Sneezing — The spray may trigger sneezing. Do not sniff after administration.
• Runny nose — Increased nasal discharge is common.
• Dry nose or throat — Some patients experience dryness rather than congestion.
• Tingling sensation — Tingling in the nose or other areas of the body.
• Fatigue — Feeling tired after the Epinephrine wears off.
• Dizziness — Mild lightheadedness may occur.
• Nausea or vomiting — Some patients feel nauseous after use.

These side effects are largely consistent with what patients experience with injectable Epinephrine. The nasal-specific effects (discomfort, sneezing, nosebleeds) are unique to Neffy's delivery method.

Serious Side Effects

Serious side effects are uncommon but can occur, especially in patients with underlying heart conditions. Seek immediate medical attention if you experience any of the following after using Neffy:

• Chest pain — Could indicate cardiac stress from Epinephrine.
• Fast or irregular heartbeat — While some increase in heart rate is normal, a very rapid or irregular heartbeat needs medical evaluation.
• Severe hypertension — Dangerously high blood pressure may occur, especially in patients already taking certain medications.
• Pulmonary edema — Fluid in the lungs causing severe difficulty breathing.
• Ventricular arrhythmias — Abnormal heart rhythms that can be dangerous.
• Angina pectoris — Chest pain caused by reduced blood flow to the heart.

Important: Even if you feel fine after using Neffy, always seek emergency medical care. Anaphylaxis can return (biphasic reaction), and you need to be monitored by medical professionals.

Side Effects in Specific Populations

Children

Neffy is approved for children aged 4 and older weighing at least 33 lbs (15 kg). Side effects in children are similar to those in adults. The 1 mg dose is used for children weighing 33 to 65 lbs, while the 2 mg dose is for those 66 lbs and above.

Patients with Heart Conditions

Epinephrine should be used with caution in patients with cardiac arrhythmias, coronary artery disease, or hypertension. These patients may be at higher risk for serious cardiovascular side effects. However, in a true anaphylactic emergency, the benefit of Epinephrine use always outweighs the risk.

Patients with Other Conditions

Use with caution if you have:

• Hyperthyroidism (overactive thyroid)
• Diabetes
• Parkinson's disease
• Renal impairment (kidney problems)
• Low potassium levels
• Structural nasal conditions (deviated septum, nasal polyps) — inform your provider as this may affect absorption

Pregnancy and Breastfeeding

In a life-threatening allergic emergency, the benefits of using Neffy during pregnancy outweigh the risks. Talk to your doctor about any concerns. If you are breastfeeding, discuss the use of Neffy with your healthcare provider.

How to Manage Common Side Effects

Most of Neffy's side effects are temporary and don't require treatment. Here are some practical tips:

• Nasal discomfort: This usually fades within minutes. Do not blow your nose immediately after using Neffy.
• Jitteriness or racing heart: This is the Epinephrine working. Sit down, stay calm, and it will subside as the medication wears off (usually within 15-30 minutes).
• Nosebleed: Apply gentle pressure to the nose. Minor nosebleeds resolve quickly.
• Nausea: Sit still and take slow, deep breaths. This usually passes as the Epinephrine effect diminishes.
• Headache or fatigue: Rest and hydrate. These effects typically resolve within a few hours.

Remember: you should always call 911 or go to the emergency room after using Neffy, even if your symptoms improve and side effects are mild. Anaphylaxis requires professional monitoring.

How Neffy Side Effects Compare to Other Epinephrine Devices

Neffy's systemic side effects (jitteriness, racing heart, nausea) are similar to those of injectable Epinephrine devices like EpiPen and Auvi-Q. The main difference is that Neffy does not cause injection-site pain, bruising, or needle-related anxiety — a significant advantage for many patients, especially children.

The trade-off is nasal-specific effects like discomfort, sneezing, and nosebleeds, which don't occur with injectable devices. Most patients find these nasal effects much more tolerable than needle-related side effects. To learn more about how Neffy compares, read our article on alternatives to Neffy.

When to Call Your Doctor

Contact your healthcare provider if you experience:

• Frequent or severe nosebleeds after using Neffy
• Concerns about how a nasal condition might affect Neffy's effectiveness
• Questions about drug interactions that could worsen side effects
• Any side effects that worry you or don't resolve

Call 911 immediately if you experience chest pain, severe difficulty breathing, or a very fast or irregular heartbeat after using Neffy.

Final Thoughts

Neffy's side effects are generally mild and temporary — especially compared to the life-threatening emergency it's designed to treat. The most common effects are nasal discomfort, jitteriness, and headache, which resolve on their own. Serious cardiovascular side effects are rare but possible, particularly in patients with heart conditions.

The bottom line: don't let concerns about side effects stop you from using Neffy in an emergency. Anaphylaxis can be fatal within minutes, and Epinephrine is the only first-line treatment. Always carry your Neffy devices and use them at the first sign of a severe allergic reaction.

Need to find Neffy at a pharmacy near you? Search Medfinder to check availability.