This is a great resource for emergency workers and first responders, particularly if you have serious or chronic medical conditions that could cause a collapse (hypoglycemia if you're diabetic, for example) or that could affect diagnosis and treatment. It's also a critical source of information on allergies you may have — particularly allergies to medications or any allergy that can be severe or life-threatening — because it increases the chances that your condition will be diagnosed appropriately and that treatment (like a dose of epinephrine for severe anaphylaxis) will be provided quickly.
Equally important can be information about medicine you're taking that may cause side effects or interact adversely with other medications an emergency physician might use to treat you.
The medical notes section can be used to keep a record of a range of important details, including recent surgeries or other medical interventions, implanted medical devices and previous hospitalizations. Notes can even be used to indicate the existence of advance directives like a do-not-resuscitate order, a living will or a healthcare proxy. If you observe a particular religion, you could even put in a request for an appropriate member of the clergy to be called if you're critically ill or injured.
You can include your doctor(s) as emergency contacts, something that's helpful in general, but particularly important if you are seeing a specialist for a serious medical condition such as cancer, because emergency personnel may need additional information from that specialist.
Even if you don't have any serious medical conditions, using this feature to list your name and your emergency contacts can still be worth the effort. After all, healthy people get into accidents and experience unexpected medical emergencies all the time. This option can also be a useful tool for parents to ensure that they are contacted right away if something happens to one of their children.
There is, of course, a caveat: Allowing lock screen access to the Medical ID panel could be a privacy concern. After all, anyone who has access to your iPhone can access this information — even people who aren't medical professionals, emergency personnel or close friends or relatives. One thing to keep in mind, however, is that someone must have physical access to your phone to look at the information — and if your phone is lost or stolen, the possibility that a stranger may be reading about your medical history isn't likely to be your biggest concern. Locating the device or wiping it using Find My iPhone would be your top priority.
If you have serious health issues or allergies, it's a no-brainer that making this information easily available is worth the minimal privacy risk. If that's not the case, you can limit the information that you present and disable access from the lock screen. (If privacy is a concern, you should know that Apple separates your Medical ID information from other Health app data and doesn't allow it to be shared with other apps that access HealthKit.) Or you can decide not to use it at all.
In the end, it's your private medical information and you have control of how to use it — or not — on your iPhone.
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