In the context of embodied theories, it has been shown the existence of shared neurocognitive processes in both self and others' affective experiences that might determine our ability to understand others. More precisely, neuroimaging studies suggested that self and others' affective states might share a supramodal representation in terms of unpleasantness and arousal, which are common properties among a large variety of aversive experiences. Nevertheless, a question still remains unresolved: is the appraisal of others' pain and disgust influenced by the same experience of the observer in modality-specific fashion or in terms of unpleasantness or arousal? To answer this question, we recruited 30 participants (10 women) to study the role of first-hand pain or disgust on the appraisal of facial expressions generated by computer. In particular, we asked participants to classify faces showing pain, disgust, surprise and neutral expressions, after receiving a comparably matched unpleasant thermal (painful) or olfactory (disgusting) stimulation. Our results indicate that the appraisal of both pain and disgust faces was biased by firsthand aversive experience. Indeed, subjects judged more frequently pain or disgust facial expressions as pain following a thermal stimulation; and inversely as disgust following the olfactory stimulation. Alternatively, thermal and olfactory stimulations did not affect the subsequent evaluation of neutral and surprise faces. In a nutshell, our data suggest that firsthand pain and disgust influence the appraisal of others' pain and disgust in terms of unpleasantness, and not arousal, neither in a modality-specific fashion.