Loved by 300,000+ people

Your MCAS health assistant

A mast cell activation syndrome tracker for reactions, triggers and meds, across every system it touches.

MCAS symptoms

The Juno app home screen with a weekly insight about flushing

A woman with her eyes closed holding her neck — After a showerFlushing and hives after a hot shower.

Features

Built for the everyday reality of managing MCAS.

Juno is designed to take some of the admin load off with calmer check-ins, clearer pattern tracking, and support that stays useful between appointments.

Flare support

Manage flares

Keep one calm place for what changed, what felt worse, and what might have triggered it so mast cell activation syndrome flare days do not blur together.

Track what changed and when
Keep notes in plain language
Spot context around tougher days

The Juno symptom tracker with mast cell activation syndrome symptoms logged today

Low-effort tracking

Track symptoms automatically

Voice or text check-ins turn skin symptoms (flushing, hives, itching), gi symptoms (nausea, cramping, diarrhoea), anaphylaxis-like episodes into a structured timeline, so you do less manual logging on already hard days.

Turn check-ins into clear logs
Keep details without filling forms
Build a timeline for appointments

A chat with Juno where a mast cell activation syndrome symptom is logged

Community

Join a community of 300,000+

Find people who understand the day-to-day reality of mast cell activation syndrome and feel less alone between appointments.

Feel less alone between visits
Read what helps other people cope
Stay connected on lower-energy days

Juno Community feed with posts about mast cell activation syndrome

Energy pacing

Manage your energy

See what is draining you and pace the week more gently around mast cell activation syndrome, especially when triggers start to stack up.

Protect tomorrow before it crashes
Notice patterns around triggers
Plan the week around your baseline

Juno pace screen showing remaining energy

From people using Juno

@paulasojoroTikTok • 350K followers

Made by Juno

@singlewithmsInstagram • 117K followers

Made by Juno

Such an incredible help

I was recently diagnosed with MS, and Juno has been a lifesaver. It helps me track everything from sleep to pain and remember what to tell my doctor.

Lvhb

Anxiety killer

Facing a doctor and needing to be assertive is hard. Juno helps me put questions into words and think more clearly about pacing.

Ginmail

Game changer

It feels like having someone who understands chronic illness with me all the time. Juno logs symptoms, remembers what helped before, and keeps cheering me on.

Jay-B23

Really great app

I can talk naturally while Juno quietly logs symptoms, mood, pain, and what I need to raise with my doctor. Tracking everything finally feels easy.

HnAWhite

Complex illness support

This is the first app that has been able to juggle all of my chronic illnesses. It helps with symptom logging, spotting correlations, and preparing for appointments.

Old ink fan

Genuinely helpful

It has actually helped me log things and understand the data myself. Sometimes Juno makes connections in my symptoms that I would have missed.

greencarnationwitch

Less alone

I have Multiple Sclerosis, and Juno has genuinely changed how I manage my days. It helps me pace my energy, track symptoms, and feel heard when I'm struggling.

kbreault421

Amazing for pacing

I had been desperate for something to track symptoms, activities, medications, and mood. Juno gives me clearer data to bring into my doctor appointments.

Lpopp3

Reviews are excerpts from published App Store reviews, lightly trimmed for length; we verify each quote against its source review and do not display incentivised reviews. Individual experiences — results vary, and Juno does not provide medical care or diagnose, treat, or prevent any condition.

Quick answer

What is the best way to track MCAS symptoms?

The best way to track Mast Cell Activation Syndrome is to separate symptoms by domain, log what changed when it happened, and connect each entry to triggers, treatment, and daily impact. Juno turns low-effort voice or text check-ins into a timeline your allergist or immunologist can review.

Starting today? Track MCAS symptoms for free: reactions, how bad they were, and possible triggers such as food, stress and weather.

Not sure which symptoms count? Read our guide to MCAS symptoms, with a printable checklist and when to get urgent help.

Living with hypermobile joints as well? Read about EDS symptoms, including the vascular EDS warning signs.

Want a simple record of each episode? Keep an MCAS symptom diary with a copyable template.

Symptom timing
Possible triggers
Treatment response
Appointment questions

What should your MCAS symptom tracker record?

A strong Mast Cell Activation Syndrome tracker records separate symptom domains, timing, triggers, treatment context, and functional impact. For Mast Cell Activation Syndrome, the most useful entries are skin symptoms (flushing, hives, itching), gi symptoms (nausea, cramping, diarrhoea), anaphylaxis-like episodes, suspected triggers (foods, scents, stress, heat), heart rate / autonomic symptoms.

How does tracking Mast Cell Activation Syndrome help at appointments?

Tracking gives your allergist or immunologist a cleaner timeline than memory can provide. It turns scattered day-to-day notes into onset, duration, recovery, possible triggers, medication context, and the questions you need answered.

When should new Mast Cell Activation Syndrome symptoms be escalated?

New, sudden, severe, or worsening symptoms should be shared with your clinical team promptly, especially when they affect daily safety, function, medication response, or a body system your care team is already monitoring. Juno helps you record what changed, but your clinician decides what needs urgent care.

What should you log?

Skin symptoms (flushing, hives, itching)
GI symptoms (nausea, cramping, diarrhoea)
Anaphylaxis-like episodes
Suspected triggers (foods, scents, stress, heat)
Heart rate / autonomic symptoms
Brain fog
Medications (H1, H2, mast-cell stabilisers) and timing
Flares (onset, severity, recovery)

What patterns matter?

Trigger candidates that recur before flares
Cumulative-load days vs single-trigger days
Medication timing and breakthrough symptoms
Overlap with POTS or EDS-related days

What should you bring?

Trigger log with what recurs and what doesn't
Flare timeline with duration and recovery
Medication adherence, timing, and breakthrough symptoms
Anaphylaxis-like episode log with epinephrine use
Specific questions for your allergy/immunology team

Tracker comparison

What makes Juno different from a generic tracker?

Generic trackers often flatten complex symptoms into one daily score. Juno keeps the details separate enough for pattern recognition and clear enough for appointments.

Need	Generic tracker	Juno
Multi-system view	Pick one system	Skin, GI, autonomic, neuro tracked together
Trigger testing	A long list of guesses	Candidates surfaced against actual flares
Medication timing	Just a list	H1/H2/stabiliser timing logged with symptoms
Comorbid overlap	Different apps	POTS / EDS data alongside MCAS
Specialist prep	Verbal recall	Page summary timed to the appointment

Key benefits

Four ways Juno makes life with MCAS a little easier.

Spot Mast Cell Activation Syndrome flare patterns sooner

Track shifts in skin symptoms (flushing, hives, itching), gi symptoms (nausea, cramping, diarrhoea), anaphylaxis-like episodes, suspected triggers (foods, scents, stress, heat) before they blur together by the next appointment.

Track symptoms automatically

Tell Juno what happened in plain language and it turns that into a clear symptom timeline without extra admin.

Protect your energy

See what tends to push you past baseline so you can pace the week with less guesswork around mast cell activation syndrome.

Show up prepared

Turn daily notes, symptom changes, and context into something your allergist or immunologist can actually use.

Private and secure.

Health conversations are personal. Juno is built so your notes, symptoms, and timeline stay yours.

Your health data should not feel exposed.

Conversations are encrypted and kept private.

We do not sell your personal health information.

You can review, export, or delete your data at any time.

Read the privacy policy

FAQs

A few common questions.

What is MCAS?

Mast Cell Activation Syndrome is a condition in which mast cells release mediators inappropriately, causing recurrent multi-system symptoms. Diagnosis is clinical, sometimes alongside specific lab criteria, and is best made by an allergy/immunology specialist. See our guide to MCAS symptoms.

Can Juno identify my triggers?

Juno surfaces what recurs before flares. Confirming a trigger usually still requires structured elimination guided by a clinician.

I have hEDS and POTS too. Will it handle that?

Yes. Comorbid conditions can be tracked alongside MCAS in one timeline rather than fragmented across apps.

Should I log epinephrine use?

Yes. Anaphylaxis-like episodes and epinephrine use are important for your specialist to know about.

Is my data private?

Yes. Health data is not sold and you control what is shared.

Other conditions

A woman sitting up in bed, silhouetted against warm evening light.

Get started with Juno.

Download the app to track symptoms, spot patterns, and feel more supported between appointments.