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You may use White petroleum jelly as a trial but this may cause condom breakage and slippage. You can try glycerine substitutes or Carrageenan. This will not be allergic to her. Make sure she is not allergic to the latex of the condom, allergy
to her sanitary pads or if she has any vaginal infection
especially if she gets any vaginal discharge
for which she will need Gynaecologist consult.