The traditional medication for overactive bladder (OAB) is antimuscarinic agent, which targets muscarinic receptors. Recent investigations have revealed that muscarinic receptors are present in the urothelium and suburothelial sensory fibers, as well as in the detrusor. Urothelial dysfunction and abnormality of sensory receptor expression or transmitter release in suburothelial nerves could contribute to OAB refractory to antimuscarinics. Intravesical treatment to inhibit abnormal receptor expression or transmitter release in the sensory nerve terminals in the suburothelial space might provide beneficial therapeutic effects in the treatment of OAB. Intravesical resiniferatoxin (RTX) instillation and intravesical botulinum toxin A (BoNT-A) injection are two promising treatment alternatives for refractory OAB. RTX at a high dose may cause undesired adverse events, such as hematuria, bladder pain or autonomic dysreflexia. RTX at a low concentration can decrease sensory urgency without influencing detrusor contractility; multiple instillations of low-dose RTX may be required to achieve adequate desensitization of OAB. BoNT-A, however, has a beneficial effect on detrusor contractility and causes large post-void residual after injection in some patients. Therefore, careful dosage and injection site adjustment is mandatory to achieve satisfactory results using intravesical therapy.