The signs
This page is shared experience and practical advice, not medical advice. It is short on purpose, so it can be read quickly when something feels wrong.
Take the cage off now for any of these. Pain that does not ease within a few minutes. Numbness, tingling or pins and needles anywhere below the ring. Skin that turns pale, blue, purple or very dark, or feels cold. Swelling. Broken skin, blisters, or signs of infection such as heat, redness that spreads, discharge or a new strong smell. Difficulty passing water.
None of these is something to wait out until a seal, the end of a day or a keyholder's answer. The lock can wait.
What to do in the next hour
Unlock and take the cage off, ring last. Rinse with plain water, pat dry and let the air get to the skin. Look at it in good light, and leave the cage off.
Mild marks from the ring usually fade within an hour or so of the cage coming off. If what you noticed settles quickly, rest and look at the fit before the cage goes back on. If it does not settle quickly, see a doctor or call NHS 111.
When it is urgent
Call 999 or go to an emergency department if the cage will not come off and the skin is changing colour, going numb or swelling, or if the pain is severe. Tell them a device is stuck; they have seen it before, and there is nothing to be embarrassed about.
For anything that worries you but is not an emergency, call NHS 111 or see your GP or a sexual health clinic. Outside the UK, use your local emergency number and urgent care line.
After it is off
Leave the cage off until the skin looks and feels as it normally does, however long that takes. Then look at why: most problems come from the fit, usually the ring, and a different size or a different cage is the usual answer, not more willpower.
Keep a note of what happened: when it started, what you noticed and what helped. If you see a doctor or nurse, it is useful to them, and next time it is useful to you.
Telling a keyholder
Nobody's permission is needed to take a cage off for your health. Tell your keyholder afterwards, plainly, if you want to. A good keyholder wants to hear it, and any arrangement worth keeping already allows for it.
Keyholders: if your sub says something is wrong, the answer is to take it off, and the conversation comes after. Never ask anybody to wait out pain, numbness or a change of colour.
Getting back in later
Go back in only when everything has settled, and start short: an hour or two while you are awake, then build up again. If the same thing happens twice, the fit needs to change before the lock goes on again.
A break for your health is not a failure and costs nothing here. On chastity.report, a lock can carry a break without ending, and an out day logged as Medical or Comfort or fit stays in your journal only.
If something hurts in a way that does not settle, take it off. The lock can wait.
Erik