Our expert says:
It is probably not real weigh gain but may be water retention. It may be due to the underlying infection or condition (like kidney problems) or other medication that you are currently taking. Moxypen does not cause weight gain or water retention although it may cause gastro-intestinal discomfort, diarrhoea, nausea and vomiting.
See also http://www.ehow.com/about_5380038_moxypen-side-effects.html
I suggest that you ask your doctor to check your kidney function.
The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal
advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.