Concussion: loss of smell & taste

Smoking cigarettes is a risk factor for developing the following diseases: mouth cancer, pharyngeal cancer, lung cancer, chronic obstructive lung disease and atherosclerotic cerebrovascular and cardiovascular diseases (heart attack and brain insult).
Smoking marijuana has the same bad consequences as smoking cigarettes, plus the drug can make a person susceptible for abusing heavier drugs like heroin, cocaine, etc.
Drinking alcohol is a risk factor for developing the following diseases: esophageal cancer, stomach cancer, chronic esophagitis and gastritis, peptic ulcer, liver cirrhosis, alcoholic myocardiopathy, alcoholic neuropathy and alcoholic psychoses.
Loss of smell and taste is probably due to some brain damage during the injury. Chances for recovery depend more upon the severity of brain damage than smoking cigarettes/marijuana and drinking alcohol. Using cigarettes, marijuana and alcohol won’t inhibit the recovery directly.... but may indirectly inhibit recover so these substances are not recommended in the next 6 months (if at all).