Rain may cause some allergies to flare up. Rain may also help ease tree pollen allergies but may worsen grass, weed, dust, and mold allergies.

Rain can wash away tree pollen, making the particles heavier and less likely to spread.

However, rain hitting grass and weed pollen can break up the particles, spreading them further and increasing exposure. Rain can also increase mold and dust mite levels, as they thrive in humid conditions.

This article discusses the link between rain and different allergies, allergy symptoms, and tips for managing allergies.

A rainy day, which may cause allergies to flare up. -1Share on Pinterest
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According to the Asthma and Allergy Foundation of America, rain may positively and negatively affect people with allergies. This can depend on the type of allergy they have.

Tree pollen counts may increase in dryer seasons as trees release more pollen. Reduced air moisture also means less moisture is weighing the pollen down, allowing it to travel easier and further in the wind.

Rain also washes tree pollen away and can prevent it from becoming airborne, reducing the amount of tree pollen in the air.

However, rain may worsen other allergies, including grass, weed pollens, mold, and dust.

When rain hits grass and weed pollen, it can break up the pollen into smaller particles. This makes the pollen spread more easily and can lead to worsening allergy symptoms, particularly with heavy downpours.

Rain can also increase mold and dust allergy symptoms, as mold and dust mites thrive in warm, humid conditions.

People may experience fewer symptoms of hay fever on rainy days because rain prevents pollen from traveling. However, it may increase exposure to it.

Although rain washes away pollen, according to the American College of Allergy, Asthma & Immunology, pollen counts can rapidly increase after rainfall.

Rain can break pollen into smaller particles, so it can become more airborne after rainfall.

Humidity can increase dust mite counts, as they require warmth and moisture to survive.

People may also be indoors more frequently in rainy seasons, which may increase their exposure to dust and other indoor allergens.

If it rains during high levels of grass pollen, it may worsen grass allergies. Rain, particularly sudden, heavy rainfall, can break up grass pollen particles and disperse them more freely, increasing exposure to the allergen.

Grass pollen counts may rapidly rise after rainfall, which may worsen symptoms for people with grass allergies.

High rainfall in the spring can increase plant growth, which can increase mold levels. If people have a mold allergy, this may cause symptoms to continue into fall.

Mold thrives with moisture and in humid environments, particularly during warmer temperatures, so rain may increase mold counts.

Symptoms of allergies can include the following:

  • a runny or stuffy nose
  • sneezing
  • wheezing
  • shortness of breath
  • a dry, persistent cough
  • rashes, including eczema, hives, and contact dermatitis
  • fatigue
  • tiredness and irritability
  • headache
  • nausea and vomiting
  • itchy eyes, nose, mouth, or skin
  • watery eyes

People can use the following measures that may help them cope better with allergies:

  • keeping windows and doors closed, including at home and in the car, during peak allergy seasons
  • using weather reports to monitor pollen and mold counts to know when they are highest and avoid being outdoors at these times if possible
  • for those with a pollen allergy, identifying which pollens they have an allergy to and checking when pollen counts are highest
  • after being outdoors, showering, washing hair, and changing and washing clothes to avoid spreading pollen or other allergens indoors
  • wearing a rated N95 filter mask when carrying out outdoor tasks, such as mowing the lawn or gardening
  • taking allergy medications before going outside
  • using air conditioning, which cools and dries out air to reduce allergens
  • avoiding hanging laundry to dry outside during periods of high allergen counts
  • taking steps to reduce dampness indoors and using detergent and water to clean any existing damp
  • using a dehumidifier to remove excess moisture in the home
  • cleaning indoor areas regularly to remove dust

Medications for managing allergy symptoms can be over-the-counter or prescription drugs and include:

Immunotherapy, which people can take as an allergy shot, is an effective treatment for seasonal allergies. People have injections that give gradual exposure to an allergen. This helps prevent the immune system from reacting to the allergen and causing symptoms.

Rain may benefit tree pollen allergies, as it can make the pollen less airborne. However, rain may worsen other allergies, including grass, weed, dust, and mold.

Limiting exposure to indoor and outdoor allergens and taking allergy medications may help people manage allergies during peak allergy seasons.