Mayo Clinic specialists answer health questions from readers like you.

• Hair dye and pregnancy: A concern?
• Hand swelling during exercise: A concern?
• Hangover prevention: Do lighter colored drinks help?
• HCG diet: Is it safe and effective?
• HCG injections: Good for weight loss?
• Headaches during pregnancy: What's the best treatment?
• Healthy chocolate: Dream or reality?
• Hearing loss: A side effect of medication?
• Heart attack prevention: Should I avoid secondhand smoke?
• Heart cancer: Is there such a thing?
• Heart disease prevention: Does oral health matter?
• Heart palpitations: A cause for concern?
• Heart rate: What's normal?
• Heavy periods: Can folic acid help?
• Heel spurs: Do they always cause pain?
• Hemorrhoids during pregnancy: What's the best treatment?
• Hepatitis C transmission: Is it safe to breast-feed?
• Hepatitis C treatment: Are herbal remedies effective?
• Hepatitis C: How common is sexual transmission?
• Hepatitis C: What happens in end-stage liver disease?
• HER2-positive breast cancer: What is it?
• Herbal treatment for anxiety: Is it effective?
• 'Herbal viagra': Is it safe?
• Hernia exam: Why do I have to cough?
• Herniated disk vs. bulging disk: What's the difference?
• Hiccups: Causes and cures
• HIDA scan (cholescintigraphy): Why is it performed?
• Hidden penis
• High blood pressure and cold remedies: Which are safe?
• High blood pressure medication: When should I take it?
• High cholesterol in children: How is it treated?
• High cholesterol treatment: Does cinnamon lower cholesterol?
• High cholesterol treatment: Necessary in older adults?
• High eosinophil count: What are the causes?
• High hemoglobin count
• High lymphocyte count (lymphocytosis): What causes it?
• High phosphorus level
• High red blood cell count
• High uric acid level: What does it mean?
• High white blood cell count
• High-dose vitamin C: Can it kill cancer cells?
• High-frequency hearing loss: Can hearing aids help?
• High-fructose corn syrup: Any health concerns?
• High-protein diets: Are they safe?
• Hip arthritis: Can hyaluronic acid injections help?
• Hip resurfacing: An alternative to conventional hip replacement?
• Hirschsprung's disease (megacolon)
• Hirsutism (excess facial hair) in women
• HIV transmission: Does anti-retroviral therapy reduce risk?
• Hoarders: When does a hobby become an obsession?
• Hodgkin's vs. non-Hodgkin's lymphoma
• Home birth: Who shouldn't consider it?
• Home enemas for constipation: Are they safe?
• Homeopathy: Good medicine or junk science?
• Honey: An effective cough remedy?
• Hoodia: Does this dietary supplement help weight loss?
• Hookah smoking: Is it safer than cigarettes?
• Hormone replacement therapy: Cause of vaginal bleeding?
• Horner syndrome: What causes it?
• Horseshoe kidney
• Hot flashes in men
• How many hours of sleep are enough?
• HPV infection: A cause of cancer in men?
• HPV infection: How does it cause cervical cancer?
• Huperzine A: Can it treat Alzheimer's?
• Hydronephrosis
• Hygiene hypothesis: Early germ exposure prevents asthma?
• Hyperbaric oxygen therapy: Can it reduce stroke damage?
• Hypercalcemia (high calcium levels)
• Hyperextended knee: Cause of serious injury?
• Hyperinflated lungs: What does it mean?
• Hyperinsulinemia: Is it diabetes?
• Hyperplasia: Is it cancer?
• Hypersomnia: What causes it?
• Hypertensive crisis: What are the symptoms?
• Hyperthyroidism: Can it cause bone loss?
• Hypnobirthing: How does it work?
• Hypoparathyroidism
• Hypothyroidism and high cholesterol: Any connection?
• Hypothyroidism and infertility: Any connection?
• Hypothyroidism diet: Can certain foods increase thyroid function?
• Hypothyroidism symptoms: Can hypothyroidism cause eye problems?
• Hypothyroidism: Can calcium supplements interfere with treatment?
• Hypothyroidism: Can it cause peripheral neuropathy?
• Hypothyroidism: Does it cause joint pain?
• Hypothyroidism: Should I take iodine supplements?
• Hypoxemia: What are the causes?
• Hysterectomy: Does it cause early menopause?