Debility is being weak or feeble. Fatigue also called exhaustion, tiredness, and listlessness is a subjective feeling of tiredness which is distinct from weakness, and has a gradual onset. Fatigue can have physical or mental causes.

Physical fatigue is the transient inability of a muscle to maintain optimal physical performance. Mental fatigue is a transient decrease in maximal cognitive performance resulting from prolonged periods of cognitive activity. It can manifest as somnolence, lethargy, or directed attention fatigue.

Causes — Fatigue is a normal result of working, mental stress, overstimulation and under stimulation, jet lag or active recreation, depression, and also boredom, disease and lack of sleep. It may also have chemical causes, such as poisoning or mineral or vitamin deficiencies, chronic blood loss, anemia.

Chronic fatigue — is a self-reported fatigue lasting at least six consecutive months. Chronic fatigue may be either persistent or relapsing. Chronic fatigue is a symptom of many diseases and conditions.

• myasthenia gravis,
• anemia and hemochromatosis
• Cancer
• Chronic fatigue syndrome
• Drug abuse including alcohol abuse^]
• Depression
• diabetes mellitus
• hypothyroidism
• Heart disease
• HIV
• Infectious mononucleosis.
• Irritable bowel syndrome
• Leukemia or lymphoma
• Liver failure
• Neurological disorders such as Parkinson’s disease and post-concussion syndrome
• Arthritis
• sleep disorders
• Stroke
• Uremia

Fatigue may also be a side effect of certain medications (e.g., lithium salts, ciprofloxacin); beta blockers, and many cancer treatments, particularly chemotherapy and radiotherapy.

Homoeopathic treatment

• Ferr Met, Ferr Phos and China – for weakness from anemia. These medicines are indicated when a person feels weak, tired and fatigued all the time. Energy levels are very low in such cases. Marked prostration is present. Such a person would usually have an aversion to any kind of physical exertion or activity because of lack of strength. Homeopathic medicines for weakness work well to aid recovery in such cases and restore energy levels by increasing hemoglobin levels.
• China and Arsenic Album – for weakness after diarrhea. China is indicated, where weakness appears following diarrhea. The blood pressure drops with weakness in such cases and the person may also faint. Ars. Alb. Is indicated when debility, exhaustion from profuse diarrhea appears. The person is prostrated with rapid sinking of body strength. Restlessness and intense thirst for water may also appear along with weakness in cases where Arsenic Album will aid recovery as one of the top rated Homeopathic medicines for weakness from diarrhea.
• Kali Carb and China – for weakness after delivery. Homeopathic medicine Kali Carb is well indicated in cases of post-childbirth weakness. Women who need to be prescribed Kali Carb have markedly low energy levels after delivering a child. Debility is usually accompanied by backache where Kali carb is indicated. China is most helpful among Homeopathic medicines for weakness where anemia and weakness follows childbirth. Rapid diminution of strength is observed in such cases. Vertigo and fainting spells may also be frequently experienced.
• Hamamelis, China and Carbo Veg – for weakness after bleeding (hemorrhage). All of them are equally effective and are prescribed in persons where excessive bleeding has led to a feeling of complete exhaustion and low strength. The blood pressure may also drop from loss of blood in such cases and the person may experience palpitations. The weakness makes it difficult to carry out normal activities like walking, talking etc.
• Gelsemium, China and Alstonia Scholaris – for weakness after fever. Gelsemium is selected when the main symptoms are marked weakness with dullness and drowsiness. There is general prostration and the pulse may also be weak and slow. China is one of the best restorative Homeopathic medicines for weakness following fever that is accompanied by debilitating sweat. Weakness following malaria fever is also best treated with China. Alstonia Scholaris is also one of the most effective Homeopathic medicines for weakness and is considered a tonic for debility resulting from exhausting fever.
• Cocculus Indicus, Carbo Animalis and Alumina – for weakness after menstrual periods (menses). Cocculus Indicus and Carbo Animalis work well where women feel exhausted from copious menses. The menses are profuse, long lasting, followed by marked weakness. In fact, the weakness is so pronounced that even speaking is a task. Alumina, on the other hand, is considered one of the best Homeopathic medicines for weakness in cases where the menstrual flow is scanty.
• Ambra Grisea and Conium — for weakness in elderly people Ambra Grisea is rated among the most useful Homeopathic medicines for weakness in aged people with sluggish bodily functions. Numbness and coldness of various body parts, useful in elderly people with concentration difficulties. Conium is another Homeopathic medicine which is profoundly helpful in elderly people suffering from weakness. Conium is selected when weakness in the elderly is most marked while walking. The gait is also uncertain, vertigo. Energy levels drop markedly while walking in such cases and the legs may feel stiff and weak. Trembling of legs and palpitations in old age.
• Selenium and Acid Phos – for weakness from loss of seminal fluids. Selenium and Acid Phos help in weakness resulting from loss of seminal fluids. They are considered the most effective Homeopathic medicines for weakness, exhaustion and debility from involuntary semen discharge while urinating, while passing stool or during sleep, no strength for any mental or physical work.
• Kali Phos and Nux Vomica – for weakness of nervous origin. Kali Phos is one of the top listed Homeopathic medicines for weakness of nervous origin. Weak memory, forgetfulness and nerve tire are all indicative symptoms for using Kali Phos. It works best when a person lacks the mental and physical strength to do any kind of work. Weakness from mental stress and worry also point towards Kali Phos. Nux Vomica is one of the ideal Homeopathic medicines for weakness that follows prolonged mental strain. Mental fatigue, including brain fag among students and businessmen, is best covered under Homeopathic medicine Nux Vomica.
• Zincum met – wonderful medicine for exhaustion of brain.