Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for trouble breathing, fainting, severe confusion, uncontrolled bleeding, or signs of shock such as cold clammy skin with severe weakness.
This service can help determine whether home observation, urgent evaluation, or emergency care is appropriate.
Arrange prompt medical review if the wound is becoming larger, more painful, blackened, or increasingly swollen, or if it develops drainage.
Seek same-day urgent care for fever, vomiting, marked weakness, pale or yellow skin, dark urine, reduced urination, rapidly spreading skin changes, or unusual bruising.
Children with possible systemic symptoms should be assessed promptly.
And for anyone, someone who:
For a mild wound without systemic symptoms, routine follow-up may involve checking that pain, redness, and swelling are improving.
Keep the area clean and follow dressing instructions.
A daily photograph taken from the same distance can help track changes.
Do not rely on a pen mark alone if redness is changing quickly.
Follow-up is also important for wounds on the face, hands, feet, or genitals and for people whose health conditions or medicines may slow healing.
The article also says
In the United States, Poison Control can provide case-specific guidance by telephone at 1-800-222-1222 .
Every sign above is quoted from the sofidex article on Brown recluse spider bite. If you are not sure, err upward — it is always reasonable to be checked.