A urinary tract infection affects as many as 8 million people every year, according to the National Kidney and Urologic Diseases Information Clearinghouse. This type of infection is caused when bacteria breach the layers of the urinary tract and immune system, infiltrating the ureters and bladder.

According to NHS, the most common causes of blisters include friction from skin rubbing against a rough surface, medical conditions such as chickenpox, herpes or eczema or a skin reaction to a product like soap, wool or hair spray, and blisters on the face can be extremely uncomfortable and embarrassing for sufferers.

Fever occurs in response to an infection, illness or disease. According to the University of Maryland Medical Center, a fever is present when the body temperature rises above 99 degrees F. A mild fever usually requires no treatment.

Brain cells may degenerate due to many illnesses, including stroke, Alzheimer’s disease and Parkinson’s disease. Once cells are damaged, the road to recovery may be long and involve physical and medicinal therapies to repair the damage and restore brain function. Natural herbs may help in this process.

There are several types of fungal infections that can affect the scalp, with ringworm being the most common. Scalp fungus can easily spread from one person to another through sharing clothes and towels. Some common symptoms of scalp fungus include split ends, dull frizzy hair and bald spots on the scalp.

Lavender has been used for treating a variety of conditions, including anxiety, insomnia, depression, headaches, hair loss and skin disorders. Lavender produces sedative, soothing effects when inhaled, according the University of Maryland Medical Center, but research does not support most other medicinal uses.

Fungal infections may sound unappealing, but they are are common and include yeast infections and athlete's foot. You can get an infection by breathing in microscopic fungus spores or having them land on your skin.

Atopic dermatitis, the most common form of eczema, causes intense itching and rashes -- primarily on the legs, arms and face. According to the National Institute of Allergy and Infectious Diseases, 30 percent of the U.S. population suffers from this skin condition.

Stomach viruses are the most common reason children vomit, according to Dr. William Sears, author of "The Portable Pediatrician." Antibiotics have no effect on viral infections; they normally go away on their own after several days, but can be very upsetting to children.

Ginger is a root herb that can be used for medicinal purposes. Ginger can be used to treat nausea, states the National Institutes of Health. Since nausea is a common symptom of acid reflux, consumption of ginger may help treat acid reflux.

Aloe vera gel is a slick substance from the interior of the thick aloe vera leaf, while aloe latex comes from just under the leaf skin. Applying aloe vera gel topically is generally considered safe, but consuming aloe vera latex or juice extracted from the latex has many disadvantages.

Commonly sold under the trade-name Pycnogenol®, pine bark extract is an herbal antioxidant supplement derived from the French maritime pine tree (Pinus maritima).