Track Long COVID. Understand Your Patterns.
Long COVID is unpredictable. Fatigue, brain fog, chest tightness, and dozens of other symptoms come and go without warning. ReactLog helps you correlate flare-ups with activity, sleep, diet, and stress—revealing what triggers your symptoms and what helps recovery. Track symptoms with real data, not guessing.
Long COVID's Unpredictability Makes It Impossible to Know What Helps
Long COVID is notoriously unpredictable. You might feel fine one day and completely exhausted the next. You get a flare-up that lasts 3 days, then another that lasts 3 weeks. Without understanding the pattern, you're left guessing at your own recovery.
The problem is that symptoms appear days or even weeks after the triggering activity. You exercise on Monday, feel fine Tuesday and Wednesday, then collapse into post-exertional malaise (PEM) on Thursday. Did the exercise cause it, or was it something else? Your diet? Sleep? Stress? You can't tell because the cause is disconnected from the effect.
Without data, you either become over-cautious and withdraw from life entirely, or you push too hard and trigger severe flare-ups. Many long COVID patients spend years without understanding their own thresholds. You bring vague descriptions to your doctor: "I get fatigued sometimes." That's not actionable information.
The solution is precise tracking. Log your symptoms daily alongside activity levels, sleep, diet, and stress. Over 2-4 weeks, patterns emerge. You discover that intense activity triggers PEM 24-48 hours later. That poor sleep magnifies brain fog. That certain foods correlate with chest symptoms. You bring concrete data to your doctor and make informed decisions about pacing and recovery.
How It Works in 3 Steps
Transform long COVID guessing into evidence-based understanding.
Log Your Days
Each morning and evening, rate your symptoms: fatigue, brain fog, chest symptoms, PEM, or any of 50+ tracked symptoms. Log your activity level from rest to high intensity. Track sleep, diet quality, and stress. ReactLog makes this quick—just sliders and ratings, not forms.
Track Over Time
Continue logging daily for 2-4 weeks. ReactLog stores everything on your phone. Don't worry about perfect data—even imperfect tracking reveals patterns. The more consistently you log, the clearer the picture becomes. You'll start noticing your own patterns emerge.
See the Correlations
After 2-4 weeks, ReactLog surfaces patterns: "Your fatigue is 40% higher on days with high activity from 24-72 hours prior" or "Brain fog improves when you sleep 8+ hours." You see which activities, foods, and conditions correlate with your worst days and your best days.
Track Everything That Matters to Your Long COVID
Comprehensive tracking for all aspects of your long COVID experience:
Core Symptoms
Fatigue, brain fog, chest tightness, shortness of breath, heart palpitations
Exertion & PEM
Activity level, post-exertional malaise onset, recovery time
Sleep Quality
Duration, quality, wake-ups, morning energy level
Cognitive Function
Mental clarity, focus, concentration, memory, brain fog intensity
Activity & Pacing
Exercise intensity, physical exertion, rest days, pacing adherence
Diet & Nutrition
Meals, trigger foods, hydration, nutritional patterns
Stress & Emotions
Stress level, anxiety, mood, emotional state, coping strategies
Custom Tracking
Create unlimited custom metrics for your unique long COVID symptoms
Your Health Data Stays on Your Phone
Why privacy is essential for long COVID tracking.
Long COVID data is sensitive. Your symptom logs reveal health conditions, disabilities, functional limitations, and vulnerabilities that you don't want shared with insurance companies, employers, or data brokers. You deserve complete privacy as you manage your recovery.
Traditional health apps collect your data and sell it to third parties. ReactLog is fundamentally different:
- No backend servers — Your symptom data lives only on your device. There is nowhere to send it.
- No analytics tracking — We don't monitor your usage patterns or symptom types.
- No data collection — We have zero infrastructure to collect anything. No servers means no data pipeline.
- No account required — You don't create a login or provide your email. Nothing identifies you.
- Face ID/Touch ID protection — Your long COVID data is biometrically locked on your phone.
We charge for the app instead of charging you with your privacy. This aligns our interests with yours. We succeed when you have the tools you need, not when we sell your health data.
Frequently Asked Questions
What is post-exertional malaise (PEM) and how can I track it?
Post-exertional malaise is a hallmark of long COVID where symptoms worsen significantly after physical, cognitive, or emotional exertion—sometimes 24-72 hours later. ReactLog lets you log activity levels daily and correlate them with symptom flare-ups over subsequent days. This reveals your personal PEM threshold so you can pace yourself appropriately and avoid severe crashes.
How can tracking help me manage long COVID?
Long COVID is unpredictable, but patterns do exist. By tracking your symptoms daily alongside activity, sleep, diet, and stress, ReactLog helps you discover what triggers your worst days and what helps recovery. You can then adjust your lifestyle accordingly and bring concrete data to your doctor to inform treatment decisions, disability claims, or medical records.
What symptoms can I track with ReactLog?
Any long COVID symptom you experience. Common ones include fatigue, brain fog, chest tightness, shortness of breath, heart palpitations, joint pain, muscle aches, headaches, sleep disturbance, cognitive difficulties, and memory problems. But you can track any symptom specific to your experience, from fever to dizziness to temperature sensitivity. ReactLog supports unlimited custom symptom entries.
Is my long COVID data private?
Absolutely. ReactLog has no backend servers and zero data collection. Your symptom logs, activity records, sleep data, and all other health information never leave your iPhone. Everything is processed on-device. You can lock the app with Face ID or Touch ID for additional security, ensuring only you can access your private health information.
Can I share my tracking data with my doctor?
Yes. ReactLog generates clear reports, charts, and summaries showing your symptom patterns and correlations. You can export this data and bring it to your doctor appointments to inform discussions about pacing, activity tolerance, treatment options, and disability accommodations. Concrete data helps doctors make better recommendations for your care.
Start tracking today.
Free during Early Access. No account required. Your long COVID data stays on your phone.