What are MCAS triggers?

Triggers are anything that causes mast cells to become activated and release mediators. Common triggers include foods, fragrances and chemicals, temperature changes, physical pressure or friction, stress (emotional or physical), infections, hormonal fluctuations, exercise, and medications. Everyone's triggers are unique, what affects one person may be well tolerated by another. Triggers can also change over time. Find out more here.

Why do my triggers sometimes seem to change from day to day?

For people with MCAS, sensitivity to triggers can vary from day to day. This may change depending on factors such as illness, stress, hormones, sleep, temperature, food, medications and other exposures. When multiple triggers are present at the same time, this can mean that something we may usually tolerate causes us symptoms. Sometimes this build up of triggers is reffered to as 'The Bucket Theory'. You could think of your body as a bucket, as different factors accumulate, stress, a triggering food, a fragrance, poor sleep, hormonal changes, etc, your bucket fills up. When it overflows, you experience symptoms. This is why the same food might cause a reaction one day but not another, depending on what else has been added to your bucket that day. Read more here.

Keeping a symptom and trigger diary can help you identify patterns over time, but it is also common for reactions to vary and for a trigger to be tolerated on one occasion but not another.

What should I do during a flare, and how long can they last?

Everyone is different, so it isn't possible to say exactly what can help you. You should speak to your healthcare team to discuss plans for flare-ups and how to best manage these. During a flare, it can be helpful to remove or reduce the trigger or triggers where possible. Your doctor may provide you with rescue medications to help manage symptoms. It may be sensible to rest, stay hydrated, and avoid additional triggers while your system is already activated. Having a written flare plan can be very helpful when you are too unwell to think clearly. If a reaction involves difficulty breathing, swallowing, or loss of consciousness, call 999 immediately. Find out more here.

How do I work out what my triggers are?

Identifying triggers takes time and a systematic approach. Keeping a detailed diary is one of the most useful tools, noting all potential triggers such as; what you ate, what you were exposed to, your stress levels, sleep, medications, and when symptoms occurred. Because reactions in MCAS are not always immediate, a diary can helps to connect things we may otherwise miss. Mast Cell Action has a free symptom tracker. Find out more about triggers here.

What is the best way to calm a flare?

Each person is unique and you should work with your healthcare professionals to make an individual plan. Common strategies include taking antihistamines or other rescue medications; removing exposure from any known trigger(s); resting; staying hydrated; and maintaining a calm, cool, quiet environment.  

Does the low histamine diet really work?

It can help some people with MCAS, but it does not work for everyone. If histamine is one of your triggers, a low histamine approach may reduce symptoms. It is important not to over-restrict your diet unnecessarily, as a very restricted diet can worsen gut health, cause nutritional deficiencies, and increase anxiety around food. Always work with a healthcare professional or dietitian. Find out more here.

Why can't my loved one with MCAS eat out or come to family meals?

Eating out can be difficult with MCAS because it is hard to control everything we might be exposed to such as; foods, preparation methods, smells, and the environment. Even small amounts of a trigger food or fragrance from other diners can cause reactions for some people. Sometimes people can plan ahead safely, but others aren't able to join in. It can be helpful to research menus in advance, call ahead, choose quieter venues, and carry safe snacks - or even bring a safe meal. Mast Cell Action has a free guide to socialising and eating out.

What medications are used to treat MCAS?

Treatment for MCAS is highly individualised because each person experiences a unique set of symptoms and triggers. Common first-line medications include H1 antihistamines (e.g. cetirizine, loratadine, fexofenadine) and H2 antihistamines (e.g. famotidine), often taken together. Mast cell stabilisers
such as sodium cromoglicate or ketotifen may also be used. Leukotriene modifiers (e.g. montelukast) are sometimes prescribed. Finding the right combination can take time, it is important to work closely with your healthcare team. Find out more here. 

How long does it take for medications to work, and how should I start them?

This varies by medication and individual circumstances. For some, antihistamines can start to provide relief within hours for others it can take much longer. Mast cell stabilisers such as sodium cromoglicate often take four to six weeks to show their full effect. A helpful principle in MCAS is 'start
low, go slow', beginning at a very low dose and titrating up gradually, introducing one medication at a time. If you have been given several medications at once, you may find it helpful to ask your prescriber whether you can introduce them one at a time to track the impact and any side effects. Side effects often improve as your body adjusts, but if they are severe or persistent, contact your prescriber. Always make changes in consultation with your healthcare team.

Can LDN (Low Dose Naltrexone) help with MCAS?

Some people with MCAS report benefit from Low Dose Naltrexone (LDN). It is thought to work by modulating immune function and reducing inflammation. LDN is not a licensed treatment for MCAS, and the evidence base is currently limited, but it is used by some specialists in complex chronic conditions. If you are interested in exploring LDN, speak to your GP or specialist. LDN must be paused 48 hours before any surgery requiring opioid pain relief.

Does mindfulness help with MCAS?

Stress can be a trigger for many people with MCAS. Mindfulness and other stress reduction techniques (such as breathing exercises, gentle yoga, or pacing) can help reduce our stress levels. They are not a cure and work best as part of a broader management approach alongside medication and trigger avoidance. Mast Cell Action has free mindfulness and wellbeing resources on its website here.

How do I cope when I feel stressed or overwhelmed?

Living with a long-term, variable, and poorly understood condition can be challenging, but you are not alone. Connecting with others who understand, through Mast Cell Action's community groups and peer support services, helps many people in our community. Speaking to a mental health professional can also make a significant difference. We have found that when managing MCAS, is can help to prioritise your emotional wellbeing alongside your physical management. Many people in our community find it helpful to join our virtual events and connect with others in a similar situation. You can find out more about our free online events here.

How do I advocate for myself in a medical appointment?

It can feel difficult to speak up and share your concerns in a medical space. Preparation can make a big difference. Some people find it helpful to write down key symptoms, when they occur, what makes them better or worse, and what has already been tried. Bringing any symptom diaries or test results can also be helpful. If you find appointments overwhelming, you might choose to bring a trusted person with you. Try to be as specific as possible about the impact the symptoms are having on your daily life. Mast Cell Action has a free resource to help you with speaking to Your GP.

How do I cope with MCAS at work?

It can be difficult for many people with MCAS to manage the workplace due to potential triggers, but also because of fatigue and pain they may experience. It can be particularly difficult when symptoms are unpredictable or severe. In the UK, the Equality Act 2010, means that employers must legally make reasonable adjustments for those with disabilities, such as flexible hours, home working, a fragrance-free environment, or rest breaks. MCAS meets the definition of a disability under the Equality Act 2010 where its symptoms have a substantial and long-term adverse effect on a person’s ability to carry out normal day-to-day activities; this is determined by the impact on the individual rather than the diagnosis alone. The Access to Work scheme can also provide practical and financial support. Mast Cell Action has resources on navigating the workplace with MCAS.

Can things get better?

Yes. Many people with MCAS find that with the right combination of medications, lifestyle adjustments, and trigger management, they are able to stabilise and regain an improved quality of life. The journey is often gradual and requires patience, but improvement is often possible. The Mast Cell Action community includes many people who have found ways to live well with MCAS. Find out more about the support available here.

How do I manage environmental triggers?

Environmental triggers such as fragrances, chemicals, temperature extremes, and mould can be some of the
most challenging to navigate as they are often difficult or impossible to avoid. Practical strategies include switching to fragrance-free products throughout the home; using a HEPA air purifier; vacuuming regularly with a HEPA-filter vacuum; using natural cleaning products; maintaining good ventilation; and asking guests to avoid wearing fragrances. Mast Cell Action has a detailed guide to managing your environment.

What can I do if my GP won't listen?

Many health professionals aren't aware of MCAS and they often have limited clinic time to discuss your symptoms, which can be challenging in MCAS where people often have multiple symptoms to share. We have developed a series of healthcare professional resources and leaflets to help you share information with your doctor. Find our resources here. You can also reach out to Mast Cell Action for help and support in working with your doctor.

How do I find a doctor who knows about MCAS?

There is currently no dedicated MCAS clinics in the NHS. Referral is usually based on symptoms and might be to allergy, immunology, haematology, gastroenterology, or another speciality, depending on your main symptoms. If you are looking for a specialist with MCAS experience, please contact us with your location, a brief description of your symptoms,and whether you are looking for NHS or private support, and the Mast Cell Action team will share relevant information about specialists in your area and other support available.

Can children have MCAS?

Yes. MCAS can occur in children as well as adults. Diagnosing MCAS in children can be particularly challenging because symptoms often overlap with common childhood conditions and because children may not be able to describe their symptoms clearly. If you suspect your child has MCAS, find out more here.

How can my child go to school with MCAS?

Schools have a legal duty of care to children with medical conditions and many will work collaboratively with families to help keep children sage in school. A healthcare plan (sometimes called an Individual Healthcare Plan or IHP) should be agreed between parents, the school, and the child's medical team. This can outline known triggers, what to do in a flare, medications they may need access to, and environmental adjustments needed, for example, avoiding fragrances in the classroom. Your child may also be eligible to and Educational Healthcare Plan (EHCP) which is a legal document detailing your child's needs and how they should be met. Some families with MCAS find that the school environment is too challenging and choose to electively home educate or seek an education other than at school package (EOTAS) with dedicated home tuition provided through their local authortiy. For more information, please get in touch.

Mast Cell Action has support for children and resources to support children in education which can be found here, in the 'Children, Young People and Education' tab. 

How can I best support someone with MCAS?

The best way to find out what support someone with MCAS needs is to ask them personally as each of us have different experiences and preferences. Learning about MCAS can be very helpful, as it allows you to understand more about what your loved-one is going through. Practical support should be guided by their unique needs and may include switching to fragrance-free products in shared spaces, if fragrance is a trigger; taking symptoms seriously even if you think the person looks well; understanding that plans may need to change at short notice; being patient with dietary needs; and helping them prepare for medical appointments. Emotional support is also very important for many people with MCAS and might include, simply listening and believing them, not minimising what they are going through and checking in on them to make sure they are ok. Find out more about here.