Will Having Botox Worsen Existing Sinus Problems?

There is no contraindication or reason against getting Botox even if you have a sinus condition. It will not worsen or ameliorate the condition. However, there is some evidence that botox injections may actually make the headaches less severe as they are currently undergoing clinical trials with migraine sufferers. Some people with migraines have headaches triggered by sinus conditions. The only problems that I have ever encountered with Botox and sinusitis is that sometimes patients complain that the needlesticks hurt a little more due to increased sensitivity in those areas. I hope this information helps.

There's no reason to worry about using Botox with your condition.  There is no link or contraindication with Botox and sinus conditions and it would not worsen your condition.  

You haven't mentioned where you want Botox injected. Regardless of the forehead, glabella (area between the eyebrows), crow's feet there should not be a reason that the sinus problems would be worsened by the Botox treatment.