So here's the real skinny on using Afrin and it's ilk for a cold.
1. You don't need to if you use a full face mask, you can just breathe through your mouth.
2. Rebound congestion won't typically develop if you do 2 things: a) only use the Afrin in one nostril per night, and b) switch nostrils each night. Don't use it if possible during the day.
3. You can use Afrin and flonase to prevent rebound congestion. See these articles:
https://www.ncbi.nlm.nih.gov/pubmed/20203244 Fluticasone reverses oxymetazoline-induced tachyphylaxis of response and rebound congestion.
Oxymetazoline-induced tachyphylaxis and rebound congestion are reversed by intranasal fluticasone.
https://www.ncbi.nlm.nih.gov/pubmed/26994623
CONCLUSIONS:
The combination of INS and Oxymet provides additional benefit compared to INS (intranasal Steroids) monotherapy in relieving nasal congestion in subjects with chronic rhinitis and allergic rhinitis without developing rhinitis medicamentosa.
Beyond this theoretical stuff, I have just spent the last 10 days treating my cold. I use nasal pillows mask (air fit P 10) so it is essential to be able to breathe through my nose during the evenings. Over the first week when my symptoms were at their worst I found using Afrin spray in at least one nostril each night to be very helpful. On any day that I used Afrin I also used Flonase. At night I also used NyQuil which contains a antihistamine as well as an anti-cough agent. This helped reduce congestion as well. During the day I mostly only used Sudafed, although I also occasionally used the Afrin. By the second week I wasn't using any of the AFRIN, although I have continued to use the NyQuil and some Sudafed during the day.
In all the years that I have been using nasal pillows masks I have lived through at least five or six colds, and have always been able to breathe through at least one nostril with the help of Afrin. If you want to take it off the table that's fine, but just recognize that you'll probably need a backup full face mask that you can tolerate.