After rinsing with chlorhexidine mouthwash, you should wait several hours before you eat or drink if you want to maximize its benefits. As a matter of fact, you can wait up to 5 hours before eating or drinking since that is how long chlorhexidine stays active in your mouth.
However, we understand that it isn't always practical to wait that long and that is why the directions for use don't explicitly say that. Their recommendation is a lot more pragmatic for your meal schedule after rinsing with it.
How to use chlorhexidine oral rinse
The chlorhexidine directions for use errs on the side of pragmatism over maximizing its efficacy. It tries to find the best middle ground so that it doesn't inconvenience your lifestyle too much.
How you should use CHX oral rinse:
After breakfast, brush your teeth and floss if possible.
Rinse with chlorhexidine for 30 seconds.
Spit out and do not rinse with water.
After dinner, brush your teeth and floss.
Rinse with CHX for 30 seconds.
Spit out and do not rinse with water.
You're supposed to use this prescription rinse twice a day but the instructions on the label specifically tell you to do it after your meals. The advantage of rinsing after breakfast and after dinner is that it allows the mouthwash to stay active in your mouth for a long period of time.
Advantages of rinsing after meals:
After breakfast rinsing ensures that you get a solid 3-4 hours of the chlorhexidine oral rinse to provide antibacterial effects before it's time for your lunch.
After dinner rinsing ensures that you get a solid 6-8 hours of the CHX rinse protecting your mouth until you're ready for breakfast.
If you rinsed before breakfast or dinner, the antibacterial effects would've been nullified or diluted once you begin eating. Doing it after your meal permits for a longer working time. This means that you get to reap the maximum benefit for your after dinner rinse but it's benefits get cut a little short for the after breakfast morning rinse.
However, it is done this way so that you don't have to fast everyday. Do you really want to have to delay your lunch for 14 days straight? How long you're supposed to use chlorhexidine is 14 days which is what the dosage regime suggests.
Waiting longer is more beneficial
Waiting as long as possible after using chlorhexidine gluconate oral rinse (CHX) before you eat or drink will provide untold benefits.
Benefits of waiting:
Take full advantage of the duration of CHX's antibacterial effect.
Eating or drinking while CHX is still coating the teeth can lead to increased staining.
Bad aftertaste can result from drinking or eating too soon after rinsing with CHX.
Of course you don't have to wait the full 5 hours but if you do, you can reap all of these advantages from using this prescribed mouthwash.
Maximize antibacterial effect
If you want to maximize the antibacterial effect of chlorhexidine mouthwash, you should wait 5 hours before you eat or drink. Yes, studies have shown that there is residual antibacterial activity in the mouth for up to 5 hours after rinsing with chlorhexidine.
Therefore, if you're able to refrain from drinking or eating, you can potentially keep your mouth in an antibacterial state for up to 5 hours. This can be incredibly helpful if you are prone to tooth decay or gum disease.
Minimize chlorhexidine staining
Chlorhexidine staining is a legitimate concern because it is a commonly known side effect. If you eat or drink while CHX is still coating your mouth and teeth, the staining can be exacerbated.
What CHX can stain:
Teeth (enamel and dentin).
Dental restorations (fillings).
The reason the staining is exacerbated if you eat or drink too soon is because CHX is positively charged while stain molecules are negatively charged. Since chlorhexidine can stay active in your mouth for up to 5 hours, that gives it plenty of opportunity to attract stain molecules.
Of course if you can make the potential staining even worse if you eat or drink extra staining foods such as coffee, tea, red wine, or tumeric.
Minimize bad taste
Eating or drinking too soon after rinsing with chlorhexidine will result in one of the most prominently felt adverse effects, a bad aftertaste. The label on the bottle of this mouthwash explicitly tells you not to rinse to minimize the bad taste.
The intense medicinal taste is worsened by rinsing with water. The same can be said if you drank water afterwards as well.
Waiting as long as you can after rinsing with chlorhexidine will provide you with the greatest amount of benefits. However, due to practicality the directions tell you to use the oral rinse after breakfast and after dinner. This ensures that you don't eat and wash away the residue in your mouth for as long as possible.
Doing it this will maximize the after dinner rinse but it does cut the after breakfast benefits a little short. If you wanted to maximize your morning rinse, you would have to delay your lunch time but most people aren't willing to do that.
Nonetheless, we believe that the directions for use are practical enough and is a good middle ground. There is no reason to fast after rinsing in the morning unless your oral condition is in dire need of assistance.