OBJECTIVE Breakthrough pain (BTP) is a transient exacerbation of pain occurring in a patient with chronic, persistent pain. The most common type is incident pain that is mostly related to bone metastases. The oral mucosa is an attractive route for drug delivery. Sublingual fentanyl preparations are a very attractive agent in controlling attacks of BTP due to its rapid absorption through the oral mucosa. Non-steroidal anti-inflammatory drugs (NSAIDs) play a key role as a first step in treatment of cancer pain; piroxicam sublingual formulations could be a useful alternative in controlling incident pain. Our study hypothesis is to evaluate the efficacy of sublingual fentanyl versus oral piroxicam fast-dissolving tablets in patients with incident pain and its impact on functional status. METHODS A cohort of 100 adults of both genders suffering from bone metastases. Patients were assigned to receive either sublingual fentanyl tablet (group 1) or oral piroxicam fast-dissolving tablets (group 2). The pain intensity reduction on a 0-10 visual analog scale (VAS), frequency of BTP attacks, and onset of pain relief. Secondary end points included the functional interference items of the Brief Pain Inventory (BPI). RESULTS There is no significant difference between the two groups regarding the patients' demographics. Significant decline of the VAS in each group in comparison to the pretreatment values (p = 0.001). Non-significant changes of the VAS, duration of pain attacks, and number of rescue doses in comparing both groups were measured. There was significant reduction in group 2 BPI regarding the relation with others, sleep pattern and enjoyment of life parameters at 2 and 4 weeks (p = 0.001). CONCLUSIONS Our study demonstrated that oral piroxicam fast-dissolving tablet is an analgesic alternative to sublingual fentanyl in patients with bone metastasis to control incidental BTP attacks with more favorable cost-benefit values.