Is it normal to feel dizzy hours after a blood test?

March 8, 2010

People have been known to feel dizzy just after a blood test .If you feel faint or dizzy sit down immediately and put your head between your knees. This could happen if you are anxious about the results, suffer from low blood pressure or if you are dehydrated. If the blood test was done on an empty stomach, your blood sugar levels might be low and this could account for the dizziness. It could also be due to the fear of needles. However, feeling dizzy hours after a blood test could be indicative of something more serious. Do contact your doctor as more tests may be required to rule out other problems.

Dizziness could be mildly annoying but could also be caused by something that is life threatening. Common causes are:-

  • Fainting from standing up too quickly or standing up too long
  • Fainting/almost fainting at the sight of blood
  • Being emotionally upset
  • Weakness during flu, cold or other illnesses
  • Vomiting or nausea
  • Motion sickness or sea sickness
  • Tiredness, fatigue, daytime sleepiness
  • Stumbling while walking

Doctors sometimes find no specific cause but dangerous causes as given below should be eliminated:-

  • Very high blood pressure which causes damage to the brain
  • Low blood pressure
  • Heart attacks, irregular heart rates or rhythms
  • Hyperventilation, stroke, tumor, headaches, migraines
  • Medications - Blood pressure medications, sedatives, tranquilizers, antidepressants, pain relievers, some antibiotics (almost all medications list dizziness as a side effect)
  • Diuretics which cause dehydration, heart effects, blood electrolyte changes or direct side effects
  • Hypoxia (low blood oxygen)
  • Hypoglycemia (low blood sugar). This includes a reaction to insulin.
  • Dehydration
  • Internal hemorrhaging which may go unnoticed
  • Anemia
  • Hardening of the arteries which causes less blood supply to the brain, heart and other organs
  • Depression, anxiety or panic disorders
  • Metabolic disorders
  • Neuropathy
  • Certain infections
  • Endocrine diseases - the pituitary gland, thyroid and adrenal glands affect salt balance ,hydration and function of other organs
  • Psychiatric reasons.

Dizziness without a clear or certain cause needs to be looked into. It is important that you visit your doctor as he/she would be able to guide you and help you deal with the problem. Losing consciousness along with dizziness would also call for urgent medical attention. Dizziness may be the only symptom of a stroke or heart attack. Prompt medical evaluation will save your life.

Submitted by M T on March 8, 2010 at 11:31

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