I took Allegra 120 for allergy, but still have a blocked nose and mild headache. Is this normal?

Dear reader,

If you’ve taken Allegra 120 (Fexofenadine) and are experiencing a blocked nose and a mild headache, these symptoms can occur for a few understandable reasons and aren’t necessarily a sign that anything is wrong.

Why These Symptoms Can Happen:

1. The medicine has started working, but not fully yet

Allegra reduces symptoms by blocking histamine, which helps with sneezing, itching, and a runny nose.

• Early relief: It usually begins working within 1–2 hours.
• Full effect: Some symptoms—especially congestion—may take a few days of consistent use to improve.

2. Nasal congestion is less responsive to antihistamines

While antihistamines are good for many allergy symptoms, they’re not as strong for blocked nose or sinus pressure.

• This means you might still feel stuffed up even though other symptoms begin to ease.
• Your doctor may later decide you need an additional treatment (such as a nasal spray) if congestion remains your main issue.

3. The headache may come from an allergic problem /congestion / viral infection like flu

Headache and allergy like symptoms are common during flu. These symtoms take few days to resolve. 

What You Should Do:

• Continue taking the medication as prescribed. Your physician has prescribed Allegra for a reason, and stopping on your own could make your allergy symptoms harder to control.
• Watch how your symptoms progress over the next few days. This helps your physician determine whether the headache and congestion are transient, allergy-related, or flu-related.
• Consult your doctor if symptoms persist or worsen. If the blocked nose or headache doesn’t improve, becomes more intense, or feels out of the ordinary, reach out to your healthcare provider. They can assess whether you need an adjustment—such as a different antihistamine or an added medicine.

Wishing you good health.