The present invention provides DMSO-containing foamable formulations, methods for preparation, and methods of treatment. The formulations can provide good permeability and bioavailability at the target site. Preferably, the formulations are useful for treating osteoarthritis. In one embodiment, the invention provides a foamable formulation for topical use, said formulation comprising DMSO, polyalkylene glycol alkyl ether, an active agent, a monohydric lower alcohol, a diol, and water. Preferably, the active agent is a non-steroidal anti-inflammatory drug, such as diclofenac sodium or ibuprofen.