ONYXOnyx is a fitness and recovery app. It is not a medical device. It is not a diagnostic tool. It is not a substitute for advice from a licensed healthcare provider.
What Onyx does
Onyx reads metrics from Apple Health and uses them to:
- Compute a daily recovery score
- Surface illness early-warning patterns when several signals shift away from your baseline at once
- Recommend training intensity and nutrition in light of your current state
- Read bloodwork you import and describe what it may mean for training
- Show heart-rhythm and fall notifications that your Apple Watch recorded
- Power Coach, an AI assistant that reasons against your data
These are signals. Useful ones. But signals can be wrong, especially in the first weeks while your baselines are still forming.
What Onyx is not
Onyx is not a diagnosis, not a prescription, not a replacement for a doctor, nurse, dietitian or physical therapist, and not a substitute for emergency care.
When to see a clinician
See a healthcare professional if you experience any of the following, regardless of what Onyx says:
- Persistent or severe symptoms: chest pain, shortness of breath, fever, dizziness
- New or worsening pain during exercise
- Symptoms that don't improve with rest
- Anything that feels seriously wrong
If you're having a medical emergency, call your local emergency number. Do not wait for Onyx to tell you something is wrong.
Specific cautions
- Illness early-warning is informational. A normal-looking score doesn't mean you're healthy. An elevated alert doesn't mean you're sick.
- Bloodwork readings are extracted from an image by an AI model and can be misread. Onyx shows you the full panel for review before saving; check every value against your original lab report. Onyx never interprets a result as a diagnosis, and any flag it raises is a reason to talk to your doctor, not a conclusion.
- Heart notifications come from Apple, not from Onyx. Irregular rhythm, high and low heart rate alerts, and atrial fibrillation burden are recorded by your Apple Watch. Onyx only shows you that they happened, because they're easy to dismiss and forget. Onyx does not interpret them and cannot tell you what they mean.
- Blood oxygen, breathing disturbances and sleep apnea notifications depend on hardware, region, and OS version. Their absence means nothing about your health.
- Recovery scores require consistent overnight wear to be meaningful.
- Training recommendations don't account for injuries, medications, or conditions Onyx doesn't know about.
- Nutrition targets come from standard formulas and your inputs. They aren't tailored to medical conditions or allergies, and where Onyx adjusts them for pregnancy or breastfeeding it uses general guidelines, not your clinician's advice.
- Coach replies are generated by an AI model and can be wrong. Verify anything important.
Pregnancy, conditions, and medications
If you are pregnant, trying to conceive, breastfeeding, managing a chronic condition (cardiovascular, metabolic, endocrine or otherwise), or taking medication that affects heart rate, sleep, or metabolism, talk to your clinician before relying on any of Onyx's recommendations. The standard formulas Onyx uses do not apply universally.
If you track your cycle in Apple Health, Onyx reads menstrual flow for exactly one purpose: so it doesn't mistake normal luteal-phase changes in heart rate, HRV and temperature for illness. It is not a fertility or contraceptive tool and must not be used as one.
Liability
By using Onyx, you acknowledge that it is not medical advice and that you are responsible for your own healthcare decisions. TheMillerBrand is not liable for outcomes from decisions you make based on the app.