Outdoor MCAS Symptom Triggers

Several things you may encounter outdoors can trigger symptoms for people with MCAS (mast cell activation syndrome):

Sunlight

UV radiation and heat can activate mast cells in the skin 

Pollen

Things like trees, grasses, and weeds can trigger histamine release

Insect stings

Bees, wasps, hornets, and fire ants release venom proteins that can activate mast cells

Temperature extremes

Hot or cold weather can destabilize mast cells

Animal dander

Proteins in dander from pets or farm animals can be irritants that lead to mast cell degranulation

Smoke

Campfires, wildfire smoke, or smoke from barbecues can inflame the respiratory system 

Humidity changes

Shifts in moisture like dampness or thunderstorms can affect airway sensitivity 

Air pollution

Ozone, smog, or vehicle exhaust can be respiratory irritants that promote mast cell activity 

Chemical pesticides

Volatile chemicals that can be inhaled or absorbed through the skin can irritate tissues and trigger histamine release 

Mold and fungi

Soil, decaying leaves, or compost can be inhaled and stimulate immune responses

Living with MCAS means it’s so important to get to know your personal triggers, so that you can help your body manage and prevent symptoms. But figuring them out can be tricky, because they’re different for everyone and not always obvious. 

Remember, the goal isn’t to shut yourself away from the outdoors—avoiding everything can actually make your body more sensitive over time. It’s about learning what your body needs so you can feel more in control and hopefully bring a little more joy back into your days.

Disclaimer: This blog post is for informational purposes only and shall not be construed as behavioral health or medical advice. It is not intended or implied to supplement or replace treatment, advice, and/or diagnosis from your own qualified healthcare provider.