Nasal decongestants, like phenylephrine and pseudoephedrine, are commonly used to relieve nasal obstruction in conditions such as allergic rhinitis. They induce nasal passage dilation through vasoconstriction but can lead to serious side effects like hypertension and rebound congestion. Despite being easily accessible over the counter, their usage patterns and awareness of side effects are not well studied. The study aimed to assess the utilization pattern and public knowledge of nasal decongestants in Al-Qunfudah governorate, Saudi Arabia, in 2023. This observational cross-sectional study assessed the utilization pattern of nasal decongestants among those who were 10 years of age and older and resided in Al-Qunfudah governorate and its villages. Data were collected in three months, from June to August 2023, using a self-administered survey that was disseminated among the general population at Al-Qunfudah governorate on different electronic platforms like Twitter (X Corp., San Francisco, CA, United States) and Snapchat (Snap Inc., Santa Monica, CA, United States). RStudio (version 4.3.0) was used for the statistical analysis. The knowledge score showed a non-normal distribution (Shapiro-Wilk test p value < 0.001). For normally distributed qualitative variables, the factors related to nasal decongestant use were assessed using Pearson's Chi-squared test. Fisher's exact test was applied when more than 20% of cells had frequencies less than 5. A generalized linear regression model was used to assess the independent predictors of higher knowledge scores. A p-value < 0.05 indicated statistical significance. Based on 410 responses, nearly 77% (n = 314) of the participants have ever used nasal decongestants. A total of 118 out of 314 (37.6%) used these medications twice daily for less than five days (81.2%, n = 255). A total of 192 (61.1%) participants used nasal decongestants based on physicians' prescriptions. Few respondents (12.9%, n = 53) and (33.2%, n = 136) correctly identified nasal mucosal ulceration and nasal dryness as adverse effects of prolonged nasal decongestants' use. However, 84.6% (n = 347) ignored their contraindications, and 55.1% (n = 226) had no idea about rebound congestion. Overall, participants displayed a moderate level of knowledge regarding nasal decongestants, with a median knowledge score of 5.0. Being a student (beta = 1.12, 95%CI, 0.19 to 2.05, p = 0.019) and being a female were independently associated with better knowledge scores (beta = 0.97, 95%CI, 0.40 to 1.54, p < 0.001). Those who ever used nasal decongestants (beta = 0.71, 95% CI: 0.07 to 1.34, p = 0.030) and those who used them three times a day (beta = 1.05, 95% CI: 0.11 to 1.99, p = 0.029) had higher knowledge scores. More than two-thirds (76.6%) of the Al-Qunfudah general population in Saudi Arabia utilized nasal decongestants. The utilization pattern of nasal decongestants highlighted short-term usage for nasal obstruction. Despite the moderate level of knowledge of the general population about nasal decongestants, many gaps were noted regarding their systemic contraindications, side effects, and the risks of rebound congestion. A focus group discussion is advised to get a full and deep perception of the public regarding this common type of medication. Health education programs are recommended regarding this category of medications, warning them about ineffective self-medication.