Is cystitis infectious?

No, it’s a bacterial infection that cannot be caught and cannot spread to another person.

It may appear to be spread by sexual contact, but the reason that it is more likely after sexual activity is because bacteria often get a chance to travel from the anal area to the urinary tract opening during sex. This is why it is helpful to empty the bladder after sex and always wipe from the front (urinary tract) to the back (anus) after using the toilet.

For the same reason, it is sensible to be careful when inserting tampons, always washing hands before and after, and avoiding bruising or otherwise damaging the tissues (making them less resistant to infection), or spreading bacteria.