The information below primarily pertains to the use of nitroglycerin for heart conditions. No serious side effects were noted in trials of nitroglycerin for osteoporosis, but headaches have been commonly reported. Tell your doctor what prescription and nonprescription medication you take, especially those to treat blood pressure, heart failure, mental illness, and nausea. And men shouldn't use nitrates if they take drugs for erectile dysfunction, such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra).
Low blood pressure (hypotension)
This can cause dizziness, light-headedness, and fainting, particularly if you stand up quickly from a lying position, are very old, dehydrated, or take other medication that lowers blood pressure. Be sure to drink enough fluids and avoid alcohol, which can worsen dizziness.
They might be throbbing, pulsating, persistent, or occasional, and range from mild to severe. Headaches were a top reason people who participated in nitrate trials for osteoporosis discontinued treatment; but they decrease over time, in some cases after a few days. Ask your doctor if you can take acetaminophen (Tylenol and generic) to prevent or reduce the severity of headaches.
Chest pain, shortness of breath, palpitations, or a heart attack might occur if you have heart problems and stop taking nitrates abruptly. "Sudden withdrawal may worsen cardiac symptoms, so potentially bone loss could be made worse also," Clarke says.
Tell your doctor if you've had anemia, glaucoma, recent head trauma, low blood pressure, or heart problems, or if you're pregnant or planning to become pregnant.
Many osteoporosis patients are small, older women who might be more sensitive to the side effects of nitrates—especially the light-headedness that could lead to falls and broken bones. "A lot of older folks get light-headed and dizzy now and then just because, and a lot are on medications that lower blood pressure," Clarke says. "Researchers will need to find a nitrate dose that minimizes these side effects yet still works for bones." The form of the medicine should also be considered. When taken as a pill and absorbed through the stomach, nitrates tend to drop blood pressure. "They may be absorbed more slowly through the skin," Clarke says, "so giving them as an ointment might reduce the side effect of lowered blood pressure and subsequent lightheadedness."