It probably is that combination of medication. See http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601070.html#side-effects for more info.
Are there other signs or symptoms present? Feeling numbness in your toes can be caused by problems with blood circulation, injury, nerve damage or even disease. However, this could also be due to some medications such as the combination of lisinopril and hydrochlorothiazide that is used to treat high blood pressure. Lisinopril is in a group of drugs called angiotensin converting enzyme (ACE) while Hydrochlorothiazide is in a class of diuretics. Tingling in the hands and feet along with dizziness, headache and cough are some of the effects that are observed in this drug combination. It is best to discuss this and any other symptoms you are feeling with your doctor for proper management. Regular monitoring of your blood pressure is also a must when taking these drug combination. Take care and keep us posted.