Many conditions, lifestyle choices, medicines, and diseases interfere with your body's ability to heal or fight infection. You may be at risk for a more serious problem from your symptoms if you have any of the following. Be sure to tell your health professional.

Conditions

• Pregnancy
• Age older than 60. Fever in older adults is more likely to mean a serious health problem.
• History of a recent head injury
• History of surgery to remove the spleen
• An invasive diagnostic or therapeutic procedure within the past 2 weeks
• Indwelling medical devices, such as artificial joints, artificial heart valves, synthetic grafts, tubes to drain body fluids (catheters), or invasive intravenous (IV) lines
• Recent exposure to an infection, such as an insect or tick bite in the past 6 weeks
• Recent heat exposure
• Recent immunization
• Surgery within the past 2 weeks
• Travel outside the country or exposure to immigrants or nonnative people
• Exposure to an untreated water source
• Exposure to raw or undercooked meat, poultry, fish, or shellfish

Lifestyle choices

• Alcohol abuse or withdrawal
• Drug abuse or withdrawal
• Smoking or other tobacco use
• Exposure to farm animals or birds

Medicines

• New medicine (within the past 3 weeks).
• Blood-thinning medicines, such as warfarin, heparin, and aspirin
• Corticosteroids, such as prednisone
• Medicines to prevent organ transplant rejection
• Medicines used to treat cancer (chemotherapy)
• Radiation therapy

Diseases

• Cancer
• Diabetes
• Gonorrhea
• Gout
• Hemophilia
• Human immunodeficiency virus (HIV) infection
• Idiopathic thrombocytopenic purpura (ITP)
• Inherited bone disease
• Kidney disease
• Lupus
• Lyme disease
• Malnutrition or an eating disorder such as anorexia nervosa or bulimia
• Multiple sclerosis
• Osteoarthritis
• Osteomyelitis
• Osteoporosis
• Rheumatoid arthritis
• Septic arthritis
• Septic bursitis
• Sickle cell disease