A swollen face due to an allergic reaction may be accompanied by other symptoms. These are the symptoms of anaphylaxis, a serious allergic reaction. Seasonal allergies, or hay fever, can occur in early spring and can cause a number of facial symptoms. This includes red, watery, itchy, and swollen eyes. Severe allergies can lead to allergic conjunctivitis, which is an oozing inflammation of the eyes.

Infections in the eyes, mouth, or salivary glands are other common causes. If you're having an allergic reaction, you may also experience hives, wheezing, or difficulty breathing.

Facial swelling doesn’t just include the face, but it can also involve the neck or throat. If there are no injuries to the face, facial swelling can indicate a medical emergency. In most cases, a medical professional should treat facial swelling.

Allergies
Your face may swell due to different allergies you may or may not be aware of.

Food allergy: Allergic reactions to food can present with swelling to the face, lips, or tongue. The reaction may also cause hives, wheezing or respiratory distress, vomiting or diarrhoea. If you are concerned about an allergic reaction, seek emergency medical attention.
Medication allergy: Allergic reactions to medications can present with swelling to face, lips, or tongue. The reaction may also cause hives, wheezing, respiratory distress, vomiting, or diarrhoea. Sometimes people develop allergic reactions to medications they have been taking for a long time. If you are concerned about an allergic reaction, seek emergency medical attention.
Environmental allergies: Allergic reactions to pollen, dust, or other environmental factors can cause facial swelling along with running nose, sneezing, and itchy, watery eyes. These allergies are not usually life-threatening. However, if you are having trouble breathing, seek emergency medical attention.