Can Flonase make you feel weird?: Understanding Potential Side Effects

October 10, 2025 •

5 min read

According to clinical trial data, adverse reactions to Flonase, such as headaches and dizziness, were reported by a notable percentage of users, though often at rates similar to placebo. So, can Flonase make you feel weird? While uncommon, some users do report unusual sensations or mood changes, which are often related to rare systemic absorption, improper use, or individual sensitivities.

Quick Summary

Some people experience unusual sensations like dizziness, anxiety, or fatigue while using Flonase, potentially due to rare systemic absorption or incorrect application.

Key Points

Common Sensations: A 'weird' feeling from Flonase is most often caused by common, mild side effects like headache, dizziness, or an unpleasant taste or smell.
Rare Systemic Effects: Systemic absorption of the steroid is low, but in rare cases, it can cause feelings of anxiety, nervousness, or fatigue, especially in sensitive individuals.
Adrenal Suppression Risk: Prolonged or high-dose use can, in rare instances, cause adrenal gland issues, leading to significant fatigue, weakness, and dizziness.
Drug Interactions: Combining Flonase with certain medications, such as ritonavir or ketoconazole, can increase systemic absorption and raise the risk of side effects.
Proper Technique is Key: Incorrect use, such as swallowing the spray, increases the risk of side effects. Following instructions helps minimize unwanted sensations.
Consult a Doctor for Persistent Symptoms: If unusual feelings persist, or you experience severe symptoms like pronounced fatigue, blurry vision, or heart palpitations, stop use and see a healthcare provider.

How Does Flonase Work?

Flonase (fluticasone propionate) is an intranasal corticosteroid, meaning it delivers a steroid directly to the nasal passages to combat inflammation. Unlike oral steroids, which affect the entire body, Flonase is designed to have a targeted, local effect. Its mechanism of action involves binding to glucocorticoid receptors in the nasal lining, suppressing the activity of multiple inflammatory mediators like histamine, cytokines, and leukotrienes. This process reduces the swelling, irritation, and mucus production associated with allergic rhinitis and other nasal issues. Because the systemic absorption (the amount of the drug that enters the bloodstream) is extremely low, serious side effects are rare. However, this does not mean they are impossible, and some individuals can be more sensitive to even minimal systemic exposure, or experience side effects due to local irritation or other factors.

Common Side Effects That Can Cause a “Weird” Feeling

While serious systemic effects are rare, several common side effects can contribute to a general feeling of being 'off' or unwell. These are typically localized or mild and may subside as your body adjusts to the medication.

Headache: As reported in clinical trials, headaches are among the most common side effects of Flonase. While not 'weird' in itself, a persistent or unusual headache can certainly make you feel strange or out of sorts.
Dizziness: A less common, but reported, side effect, dizziness can create a disoriented or unsteady sensation. Some user reviews specifically mention dizziness, sometimes alongside other symptoms.
Unusual Tiredness or Weakness: Some users report experiencing unusual fatigue or a feeling of weakness. This can be a symptom of a more serious issue like adrenal suppression, but for most, it is a milder, temporary side effect.
Unpleasant Taste or Smell: An altered sense of taste or smell can result from fluticasone nasal spray, which can be an unsettling and unpleasant experience.
Nasal Irritation or Dryness: A raw or irritated feeling inside the nose or throat, while localized, can feel very strange and distracting.

Psychological and Neurological Side Effects

More concerning, though far less common, are the psychological and neurological side effects that can make a person feel truly 'weird'. User reports, though not clinically verified, highlight a few specific issues.

Anxiety and Nervousness: Some individuals, particularly those with a history of anxiety, have reported a worsening of their condition or even panic attacks after using fluticasone. While clinical studies do not list anxiety as a common side effect for the nasal spray, the link is strong enough in user reports to warrant attention. This can occur due to the minimal systemic absorption of the steroid.
Brain Fog: The term 'brain fog' is often used to describe feelings of confusion, difficulty concentrating, or a general sense of mental slowness. Some users attribute this sensation to Flonase use.
Mood Changes and Insomnia: Altered mood, irritability, or sleeplessness are sometimes mentioned in user reviews, especially when discussing a broader 'weird' feeling.

Causes of Systemic Side Effects

For most people, the minute amount of fluticasone absorbed systemically is insignificant. However, certain factors can increase this absorption and the risk of side effects:

Dosage and Duration: Taking higher than recommended doses or using the spray for an extended period can increase the likelihood of systemic absorption and associated side effects.
Improper Technique: If the spray is not used correctly and ends up dripping down the back of the throat, it may be swallowed. This increases the amount of drug absorbed by the digestive system, although oral bioavailability is still low.
Drug Interactions: Certain drugs, particularly potent CYP3A4 inhibitors like ritonavir (used for HIV) and ketoconazole (used for fungal infections), can interfere with the body's metabolism of fluticasone. This can significantly increase plasma fluticasone levels, leading to systemic effects.
Adrenal Suppression: In rare cases, chronic or high-dose use of corticosteroids can suppress the adrenal glands, which produce natural steroid hormones. Symptoms of adrenal insufficiency include severe fatigue, weakness, dizziness, and low blood pressure, all of which could be described as feeling 'weird'.

Comparison of Flonase (Fluticasone) vs. Other Allergy Medications

Understanding how Flonase compares to other common allergy medications can provide context for its side effect profile.


Feature	Flonase (Fluticasone) Nasal Spray	Oral Antihistamines (e.g., Cetirizine, Loratadine)	Oral Steroids (e.g., Prednisone)
Mechanism	Local, intranasal anti-inflammatory effect	Systemic histamine blocker	Systemic, potent anti-inflammatory effect
Primary Target	Nasal passages	Entire body	Entire body
Effectiveness	Highly effective for nasal symptoms and inflammation	Effective for general allergy symptoms (itching, sneezing)	Powerful, reserved for severe cases
Common Side Effects	Nasal irritation, dryness, headache, unpleasant taste/smell	Drowsiness (older generation), dry mouth, blurred vision	Nausea, headache, dizziness, insomnia, mood changes
Systemic Side Effects	Rare, low absorption	Common, depending on the drug and dose	Common and more severe

How to Minimize the Risk of Feeling “Weird”

If you are concerned about potential side effects from Flonase, here are a few tips to help minimize your risk:

Use the Correct Technique: Always follow the instructions for use. Spray away from the nasal septum (the center wall of your nose) and avoid inhaling too deeply to prevent it from dripping down your throat.
Use the Lowest Effective Dose: The goal is to use the minimal dose that provides symptom relief. If you are using it long-term, your doctor may recommend titrating down to a lower dose.
Consult Your Doctor: Before starting Flonase, discuss your medical history, including any history of anxiety or mood disorders. Also, inform your doctor of any other medications you are taking to check for potential drug interactions.
Avoid Excessive or Long-Term Use: For over-the-counter versions, be mindful of the duration of use. If you need it for longer than recommended, consult a doctor.

Conclusion

While Flonase (fluticasone) is generally considered a safe and well-tolerated treatment for nasal allergies, the potential to feel 'weird' is a genuine concern for some users. The feelings of dizziness, fatigue, and headaches are documented common side effects, and rare instances of systemic absorption can lead to more unusual sensations like anxiety or mood changes, as reported in user experiences. Awareness of these possibilities, along with proper usage techniques and communication with your healthcare provider, is key to ensuring the medication works effectively and safely for you. If any 'weird' feelings persist or are severe, it is best to stop using the product and seek medical advice promptly.

For more in-depth information on Flonase side effects, refer to the detailed product information on Drugs.com(https://www.drugs.com/sfx/flonase-side-effects.html).

Frequently Asked Questions

While not listed as a common side effect in clinical studies, user reports on sites like Drugs.com do mention experiences of increased anxiety, nervousness, and even panic attacks, suggesting a link for sensitive individuals. If this occurs, stop using the medication and contact your doctor.

Dizziness is a known, though less common, side effect of Flonase that has been reported in clinical trials and user experiences. If the dizziness is severe or persistent, it is important to contact a healthcare professional.

Unusual tiredness or weakness is listed as a potential side effect. While typically mild, it can also be a symptom of a rare but serious condition called adrenal suppression, especially with long-term use. Report this to your doctor if it is severe or doesn't improve.

To minimize systemic absorption and side effects, always use the lowest effective dose, follow proper spraying technique, and inform your doctor of any other medications you are taking to check for interactions.

The term 'brain fog' is used by some users to describe feelings of mental confusion or difficulty concentrating that they associate with Flonase use. While not a formally recognized symptom, it could be related to rare systemic effects or general malaise.

If you experience strange or unusual feelings that you believe are caused by Flonase, you should stop using it and contact your doctor. They can help determine the cause and recommend an alternative treatment if necessary.

Yes, Flonase can interact with strong CYP3A4 inhibitors like ritonavir (an HIV drug) and ketoconazole (an antifungal), which can increase the level of fluticasone in your body and heighten the risk of side effects. Always inform your doctor of all medications you are taking.