Abstract: Described herein are single domain VHH polypeptides (antibodies) that bind to and/or neutralize the cytokine interleukin 6 (IL-6), in particular, human IL-6 (hIL-6). Anti-hIL-6 VHH polypeptide products, methods, pharmaceutical compositions, and kits are provided for treating a subject having or at risk of having a disease, disorder, pathology, or infection associated with or induced by IL-6 or dysfunctional IL-6 signaling. The methods, compositions and kits include a single domain, anti-hIL-6 VHH polypeptide (antibody), or hIL-6 binding portion thereof, that specifically binds to and/or neutralizes IL-6 and treats or prevents IL-6-induced illnesses and diseases. The anti-hIL-6 VHHs, or hIL-6 binding portion thereof, may be recombinantly produced and expressed.