Thank you for writing to us.
I do not think this would cause a long-term issue. The reason to use it as soon as possible would be that vitamin B is degraded quickly. This will cause it to be ineffective.
I do not think that it can cause any infection as the infection caused by it would have shown up very early. If you want to be absolutely sure, you can talk to a Doctor or prepare the syrup again and get it tested for any problems.
I hope this helps you.
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