Allergy symptoms can be categorized as mild, moderate, or severe.

Mild allergy symptoms can include:
- Rash
- Itchy, watery eyes
- Congestion

Mild allergic reactions do not spread to other parts of the body.

Moderate allergic reactions can include symptoms that spread to other parts of the body, including:
- Itchiness
- Difficulty breathing

Anaphylaxis is a rare, life-threatening emergency in which the body's response to the allergen is sudden and affects the whole body. Allergy symptoms may begin with sudden itching of the eyes or face and within minutes progress to more serious symptoms, including:
- Varying degrees of swellings that can make breathing and swallowing difficult
- Abdominal pain
- Cramps
- Vomiting
- Diarrhea
- Mental confusion or dizziness