Administration

• Hydralazine used to treat high diastolic blood pressure is most often taken two to four times a day as directed by a physician. According to RxList, this medication is administered as an injection into a muscle or as a pill taken orally. Patients often start at a lower dose and slowly increase to a dose that their doctor feels is the most beneficial. All doses must be taken at the same time daily.
  
  

Contraindications

• Certain medical conditions may prevent a patient from being able to take hydralazine to treat high diastolic blood pressure. According to RxList, these include allergies, mitral valve heart problems, heart conditions, history of stroke, blood vessel problems and kidney problems.
  
  

Side Effects

• Patients taking hydralazine to treat high diastolic blood pressure can experience side effects. According to RxList, common side effects include headache, dizziness, pounding heartbeat, diarrhea, fast heartbeat, nausea, loss of appetite and vomiting. The serious side effects include tingling, numbness, chest pain, severe tiredness, jaw pain, aching joints, left arm pain, swollen joints, bruising easily, cheek and nose rash, bleeding easily, swollen glands, signs of infection, urine amount change, pink urine and bloody urine.
  
  

Drug Interactions

• Patients taking certain medications may not be able to take hydralazine at the sime time. According to RxList, these include MAO inhibitors, cough medications, cold medications, diet aids and over-the-counter pain-relieving medications. MedicineNet states that diazoxide and beta-blockers may also interact. Drugs.com states that tizanidine may also interact.
  
  

Risks and Warnings

• According to RxList, patients should never stop taking this medication without their doctor's consent because doing so could result in a worsening of their condition. Patients may not be able to drive on this medication due to dizziness. Elderly people may be more vulnerable to experiencing side effects. Pregnant and breastfeeding women should consult their doctor before starting hydralazine. Patients with a nitrate allergy should not take this medication.