I think at the beginning of the UTI infection( when you first feel any burning or urgency) or atrophy related burning, you can actually clear the infection and discomfort by drinking lots of water, and the bicarb of soda relieves the burning with the awful feeling you need to pee all time. So the sachets bought at the chemist, if used early on, could essentially clear things because it basically encourages you to drink lots as well. BUT you don't need to buy the sachets as you can just use the half a teaspoon of bicarb in a glass of water 3 times a day for 2-3 days but you must also drink enough water throughout the day as well.
Too many women stop drinking when they get a UTI because they think it will make the need to pee worse - whereas drinking more will actually help. It needs to be water as most other drinks like fruit juices, tea or coffee are bladder irritants. When you have an infection or there is atrophy, the urethra and lower bladder becomes inflamed and I believe this is what causes the need to pee a lot, as it's the body trying to clear out the concentrated and acidic urine that is irritating this sore area.
I am not a medical professional but I did see an excellent Youtube film done by an American Uro/gynae explaining about this problem and how he treated it. Here in the UK, the urologist I saw told me he believed it is scare tissue from past infections and menopausal atrophy that causes these UTI type symptoms but I know there is now some research that shows some women have deep seated infections that need long term antibiotics. The Urologist I saw still called it interstitial cystitis which is a term used when they really don't know what is wrong!!!
I think it is accepted (recommended in the NICE guidelines) that by using local oestrogen this will plump up the skin of the vagina, bladder and urethra making it healthier and less likely to become inflamed.
Here is the section from the NICE guidelines about urogential atrophy:
Urogenital atrophy
1.4.9
Offer vaginal oestrogen to women with urogenital atrophy (including those on systemic HRT) and continue treatment for as long as needed to relieve symptoms.
1.4.10
Consider vaginal oestrogen for women with urogenital atrophy in whom systemic HRT is contraindicated, after seeking advice from a healthcare professional with expertise in menopause.
1.4.11
If vaginal oestrogen does not relieve symptoms of urogenital atrophy, consider increasing the dose after seeking advice from a healthcare professional with expertise in menopause.
1.4.12
Explain to women with urogenital atrophy that:
symptoms often come back when treatment is stopped
adverse effects from vaginal oestrogen are very rare
they should report unscheduled vaginal bleeding to their GP.
1.4.13
Advise women with vaginal dryness that moisturisers and lubricants can be used alone or in addition to vaginal oestrogen.
1.4.14
Do not offer routine monitoring of endometrial thickness during treatment for urogenital atrophy.
DG x