There’s no simple rule for when a wound needs antibiotics. They are clearly part of treatment for one named condition, and it is worth being clear about the difference.
Cellulitis is a bacterial skin infection affecting the middle layer of the skin and the tissues below. If you have it, you will likely be prescribed antibiotics to take by mouth, and you may be given pain medicine as well if needed. Cellulitis usually goes away after taking antibiotics for 7 to 10 days, and longer treatment may be needed if it is more severe.
Sometimes tablets by mouth may not be enough. A hospital stay may be needed if you are very sick, for example with a very high temperature, low blood pressure, or nausea and vomiting that does not go away; if you have been on antibiotics and the infection is getting worse, spreading beyond the original pen marking; if your immune system is not working well; if the infection is around your eyes; or if you require antibiotics through a vein.
For wounds in general, it works differently. The signs of infection tell you when to contact a provider. What the provider then decides depends on the wound, and this page won’t guess at it.
One thing is clear about what not to do in the meantime: do not apply antibiotic cream or other products unless your surgeon tells you to, and do not put any lotion, cream, or herbal remedies on or around your wound unless your provider has said it is OK.
And one thing worth knowing: with ischemic ulcers, medicine is part of restoring blood flow, not a substitute for it. Antibiotics are not the only kind of medicine a wound may need.
The question you can act on is when to be seen. The signs of infection — redness, increased warmth or swelling around the wound, more or cloudy drainage, bleeding, odor, fever or chills, increased pain — are the trigger for a conversation in which antibiotics may or may not be the answer.