How long do allergy symptoms really last?

A sudden skin rash, persistent sneezing, or itchy eyes – allergic reactions can be unpleasant and vary in duration. While some symptoms subside within minutes, others may last for days or even weeks. But what determines how long an allergy lasts?

In this article, you will learn about the different types of allergic reactions, how long typical symptoms persist, and which factors influence their duration. Additionally, you will receive tips on when to seek medical advice and how to alleviate allergic symptoms as quickly as possible.

Table of Contents

• What is an allergy?
• Classification of allergic reactions by reaction time
• Overview of different allergy types
• How long do typical allergy symptoms last?
• Factors influencing the duration of an allergic reaction
• How to quickly relieve an allergic reaction
• Summary

What is an allergy?

An allergy is an excessive reaction of the immune system to normally harmless substances, known as allergens. The body mistakenly perceives these substances as a threat and triggers defense mechanisms, leading to typical symptoms such as itching, rashes, sneezing, shortness of breath, swollen eyes, or digestive problems, all of which characterize an allergic reaction (Cleveland Clinic, 2022).

Classification of allergic reactions by reaction time

Allergic reactions can be categorized based on the time frame in which symptoms appear after exposure to an allergen:

• Immediate-type allergies (minutes to hours): The most common type, where the immune system reacts immediately after allergen exposure. Symptoms such as rashes, breathing difficulties, or itching occur within minutes to a maximum of two hours.
• Delayed-type allergies (24–72 hours): This reaction is delayed because special immune cells, rather than antibodies, are involved. Typical symptoms include skin reactions that become visible one to three days after exposure.
• Chronic allergies (weeks to months): This form involves persistent or recurring symptoms when allergen exposure is not avoided. These are often environmental allergies that cause long-term discomfort.

Source: Allergy and Asthma Network, 2025

Overview of different allergy types

Inhalation Allergies

Inhalation allergies occur when allergens are absorbed through the respiratory tract, primarily affecting the airways and eyes. Depending on the allergen, symptoms may be seasonal or year-round.

Symptoms & Duration: Sneezing, itchy eyes, blocked or runny nose, breathing difficulties. Symptoms usually appear immediately and persist as long as the allergen is present.

Examples:

• Pollen allergy (hay fever): Seasonal symptoms, immediate-type reaction.
• House dust mite allergy: Year-round symptoms, chronic.
• Mold allergy: Symptoms depend on mold exposure, chronic (long-term).
• Pet dander allergy: Symptoms appear upon contact with animals, commonly triggered by cats or dogs.

Contact Allergies

These allergies develop through direct skin contact with certain substances. The reaction is usually delayed and primarily manifests as skin changes.

Symptoms & Duration: Skin redness, itching, blistering, dry skin. The reaction appears 24–72 hours after contact (delayed type) and can last several days.

Examples:

• Nickel allergy: Triggered by jewelry or metal buttons.
• Fragrance allergy: Caused by perfumes or cosmetics.
• Latex allergy: Often results from gloves, medical products, or condoms.

Food Allergies

In food allergies, the immune system overreacts to certain proteins in foods. Even tiny amounts can trigger symptoms, ranging from mild skin reactions to life-threatening conditions.

Symptoms & Duration: Itching in the mouth and throat, rashes (e.g., hives), swelling of the lips, tongue, or face, as well as digestive issues like nausea, vomiting, or diarrhea. Severe cases may lead to breathing difficulties or anaphylaxis. Symptoms typically appear within minutes to two hours (immediate type), though delayed reactions (24–72 hours) are also possible.

Examples:

• Peanut allergy: Often causes severe reactions, immediate-type.
• Milk protein allergy: Mainly affects children, immediate or delayed type.
• Shellfish allergy: Common in adults, immediate-type.

Drug Allergies

A drug allergy occurs when the body mistakenly identifies certain medications as harmful and triggers an immune response.

Symptoms & Duration: Rashes, itching, swelling, fever. Severe reactions may include breathing difficulties or circulatory collapse. Symptoms can appear immediately or be delayed (24–72 hours).

Examples:

• Penicillin allergy: May cause delayed skin reactions or immediate responses.
• Painkiller allergy (e.g., ibuprofen or aspirin): Often a delayed-type reaction with skin symptoms.
• Contrast agent allergy: Can trigger severe immediate reactions.

Insect Venom Allergies

This type of allergy occurs after being stung by bees, wasps, or other insects. Severe cases can result in anaphylactic reactions, which are life-threatening.

Symptoms & Duration: Severe swelling, redness, itching at the sting site; in serious cases, circulatory issues and breathing difficulties. Symptoms usually appear within minutes (immediate-type).

Examples:

• Bee sting allergy
• Wasp sting allergy
• Hornet sting allergy

Sources: MedlinePlus, 2024; NHS, 2022; Mayo Clinic, 2024; AAFA, 2015

How long do typical allergy symptoms last?

The duration of an allergic reaction depends not only on the allergen but also on individual factors. Some people react more sensitively and for longer periods than others. The following table provides general guidelines on how long typical symptoms may last, but reactions can vary individually.

Note: If symptoms persist longer than expected or worsen, medical advice should be sought (Allergy and Asthma Network, 2025).

When should medical advice be sought?

In most cases, allergic reactions are unpleasant but harmless. However, a doctor’s visit is necessary if:

• Severe shortness of breath or chest pain occurs.
• Swelling in the face or throat develops.
• An allergic reaction lasts longer than a week.
• Medications do not work or symptoms worsen.

In cases of anaphylactic reactions (sudden blood pressure drop, breathing difficulties, circulatory failure), emergency medical attention is required immediately (Cleveland Clinic, 2022).

Factors influencing the duration of an allergic reaction

The duration of an allergic reaction depends not only on the type of allergy but also on several individual and environmental factors. While some symptoms subside within minutes, others can persist for days or even weeks.

• Amount and Type of Allergen: The larger the amount of allergen absorbed, the longer and more intense the reaction may be. For example, minimal contact with pollen may cause only mild irritation, whereas consuming an allergy-triggering food can lead to hours of symptoms or even life-threatening reactions.
• Individual Sensitivity: Some people are particularly sensitive to certain allergens and experience prolonged symptoms, while others may become symptom-free within a short time.
• Treatment and Countermeasures: Taking antihistamines in time or avoiding further allergen exposure can shorten the reaction. Without treatment, symptoms may persist longer.
• Intrinsic Factors: The immune system plays a crucial role in how quickly the body recovers from an allergic reaction. People with weakened immune systems or pre-existing skin conditions (e.g., atopic dermatitis) tend to experience longer-lasting symptoms.
• Duration of Allergen Exposure: In chronic allergies, such as those triggered by dust mites or mold, symptoms may persist as long as the allergen exposure continues.

Sources: Wu et al., 2021; Cleveland Clinic, 2023

How to quickly relieve an allergic reaction?

Allergic reactions can often be alleviated or even prevented if the right measures are taken in time. Here are some proven strategies:

✔ Avoid allergens: The best protection is to minimize contact with known allergy triggers—for example, by using special pollen filters, hypoallergenic bedding, or an allergen-reduced diet.

✔ Use medication: Antihistamines can help mitigate immediate reactions, while corticosteroids are effective for more severe reactions. In cases of severe allergies, an emergency kit with adrenaline may be necessary.

✔ Protect skin and mucous membranes: For contact allergies, avoiding irritating substances and using lipid-replenishing creams can help. Inhalation allergy sufferers benefit from nasal rinses and air purifiers.

✔ Consider desensitization: This long-term therapy can help the immune system adapt to an allergen and reduce allergic reactions. Over several months to years, the allergen is gradually introduced in increasing doses by a doctor—either as an injection (SCIT) or in tablet/drop form (SLIT). It is particularly effective for pollen, dust mites, and insect venom allergies and can reduce symptoms long-term, in some cases by up to 80% (Bernardini et al., 2024; UMC Utrecht, 2025).

✔ Take immediate action: For mild reactions, cooling (for skin reactions), drinking plenty of fluids (for food allergies), or removing the allergen (e.g., nasal rinses after pollen exposure) can help.

✔ Seek medical advice: Those suffering from severe or recurrent allergies should consult an allergist to develop targeted treatment strategies.

Sources: MedlinePlus, 2024

Allergy Testing – What are the options?

If you suspect that you have an allergy, an allergy test can help identify the triggers. With Homed-IQ home tests, you can quickly and reliably gain clarity:

• Comprehensive Allergy Test – Tests for over 295 allergens, including pollen, pet dander, dust mites, food allergens, and insect venom—ideal if you are unsure about your triggers.
• Inhalation Allergy Test – Specifically designed for respiratory allergies such as hay fever or dust mite allergy. It analyzes airborne allergens like pollen, pet dander, and mold spores.

Both tests are based on a blood analysis that you can conveniently perform at home. The sample is analyzed in a certified laboratory, and you receive a detailed report on your allergies—all without the need for a doctor's visit.

Summary

The duration of an allergic reaction can vary significantly—from a few minutes to several weeks. While immediate-type allergies usually appear within minutes and subside within a few hours, delayed-type allergies develop 24–72 hours after exposure and last longer. Chronic allergies can cause symptoms for months if allergen exposure persists. The duration of allergic reactions depends on the type of allergen, individual sensitivity, and possible countermeasures.