I am on ranitidine at the moment & i've got very itchy armpits (develops at night), itchy & slightly painful breasts. is this due to ranitidine?

You may have allergy: If the symptoms began after taking the medication there is a strong possibility you might be allergic. I would stop the pills and see your family doctor.

Could be?: These types of medications, especially Cimetidine (tagamet) are know to cause breast tenderness. Itching? I am not so sure about, however, if there is a one on one correlation to taking a medication and developing symptoms, there is a good chance it may be the cause. One can stop and see if symptoms go away and restart and see if they recur? May just want to go to a different med. Ask your pcp?