Can I get cortisone shots while breastfeeding?

Yes, but... Cortisone injections are not specifically a contraindications- but there are often non-invasive treatments for many of the same conditions. There range from icing to physical therapy to acupuncture. A physiatrist can help identify options for you.
Yes. Cortisone shots or taken by mouth for that matter, appear to have no significant effect upon a breast fed baby or lactation.

Related Questions

Do you also (as my doctor) see ok to get a cortisone shot and dimetinden therapy when breastfeeding (1 month old baby) due to a heavy nettle rash?

Probably. Some of the medications you take will get into the breast milk but given the severity of your rash, i think the risk /benefit ratio favors taking the medications since the medications would be present in only trace quantities and not likely to affect your infant. How did you get a nettle rash in an austrian winter? I'd have thought that an edelweiss rash would be more likely :)). Read more...