Many conditions, lifestyle choices, medications, and diseases interfere with your 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

• Younger than age 5
• Older than age 65
• Obesity
• Previous heat-related illness
• An illness that causes dehydration (for example, an illness with vomiting or diarrhea)
• Recent burns, including sunburns

Lifestyle choices

• Alcohol abuse or withdrawal
• Drug abuse or withdrawal. Illegal drugs, such as methamphetamines, amphetamines, cocaine, heroin, PCP (phencyclidine hydrochloride), and LSD (lysergic acid diethylamide), also affect your ability to sense dehydration or heat-related symptoms. These substances also reduce your judgment about whether treatment is needed for a heat-related illness.
• Smoking or other tobacco use

Medications

• Anticholinergics, such as atropine and scopolamine
• Antidepressants
• Antihistamines, such as Benadryl and nonprescription cold remedies
• Benztropine mesylate
• Blood-thinning medicines, such as warfarin, heparin, and aspirin
• Cardiac drugs, such as beta-blockers and calcium channel blockers
• Corticosteroids, such as prednisone and dexamethasone
• Diuretics, such as Lasix and hydrochlorothiazide
• Phenothiazines
• Medications to prevent organ transplant rejection
• Medications used to treat cancer (chemotherapy)
• Medications used to treat Parkinson's disease
• Radiation therapy
• Sedatives, such as Haloperidol
• Thyroid hormones

Diseases

• Cancer
• Cystic fibrosis
• Diabetes
• Heart disease
• Hemophilia
• Human immunodeficiency virus (HIV) infection
• Hyperthyroidism
• Idiopathic thrombocytopenic purpura (ITP)
• Kidney disease
• Lupus
• Malnutrition or an eating disorder such as anorexia nervosa or bulimia nervosa
• Multiple sclerosis
• Parkinson's disease
• Peripheral arterial disease
• Pheochromocytoma (endocrine abnormality)
• Skin diseases, such as psoriasis, scleroderma, or eczema
• Stroke