Interactions at normal doses are usually moderate, jackson. Opiates and benzodiazepines are often used together to treat pain and are usually well tolerated.
Both may act as central nervous system depressants which may affect mental alertness, motor coordination, and respiration (breathing). Do not use hazardous machinery until you are able to gauge how these drugs affect you. Driving is probably inadvisable, not only because of any potential affects on ability, but also legal and insurance issues. Taken long term there is a small risk of developing clinical depression.
If they have been prescribed by the same physician that doctor will have taken potential interactions into account and determined that the benefits outweigh any likely side-effects. Do not stop taking either medication without checking with the doctor first.
If they have been prescribed by different physicians and they are unaware of the other medication(s) you are taking you should tell them asap.
Best wishes
Ian
NOTE: I am not a doctor, and more importantly, I'm not your doctor so the above advice is necessarily of a general nature which may or may not apply to you. Always consult your health provider before acting on anything you've read here.
Posted by jackson