3. Heat intolernce

4. Heat intolerance is unusual sensitivity to heat (feeling hot when others feel comfortable or even cold
Heat intolerance is not a disease ,but it can be symptom of an underlying medical condition

5. symptoms exhaustion and fatigue during warm weather
nausea, vomiting, or dizziness in response to heat
changes in mood when too hot
Feeling very hot in moderately warm temperatures
not sweating enough in the heat .

6. causes
Dysautonomia
Those with heat intolerance may have a disorder called dysautonomia that affects their autonomic nervous system.
Several medical conditions can cause dysautonomia, including:
Diabetes
Alcohol use disorder
Parkinson’s disease
Guillain-Barre syndrome

7. causes
Medication: One of the most common causes of heat intolerance is medication. Antihistamines (diphenhydramine), Antihypertensives (clonidine, and decongestant medications are among the most common .anticholinergic as atropen, Bladder antispasmodics (oxybutynin, Antiepileptics (topiramate, Opioids (fentanyl, morphine.
Caffeine is a stimulant that can increase your heart rate and speed up your metabolism. This can cause your body temperature to rise and lead to heat intolerance

8. Causes
Neurological conditions: Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system
Endocrine system problems: Hyperthyroidism occurs when your thyroid produces too much of the hormone thyroxine. Thyroxine affects the regulation of your body’s metabolism. An excess of this hormone can cause your body’s metabolism to increase, which leads to a rising body temperature.
Anhidrosis

9. Anhidrosis
Anhidrosis is a condition in which you can’t sweat.

10. Causes of anhidrosis
Skin damage from burns, radiation therapy, or pore-clogging diseases such as psoriasis.
Damage to the sweat glands from surgery, trauma or scar formation.
Nerve damage caused by diabetes, alcoholism, and Guillain-Barre syndrome.
Inherited disorder of the metabolic system (Fabry disease).

11. Causes of anhidrosis
Connective tissue disorders, such as systemic sclerosis, systemic lupus erythematosus, Sjogren syndrome
Autonomic nervous system disorders, such as Ross syndrome, and Harlequin syndrome.
Nerve conditions (neuropathies), such as diabetic neuropathy, paraneoplastic neuropathy, inherited neuropathy, amyloid neuropathy, lepromatous neuropathy.

12. Causes of anhidrosis
Central nervous system diseases and conditions, including multiple system atrophy, dementia with lewy bodies, Parkinson's disease, stroke and spinal cord disease.
Excessive dehydration.
Genetic disorder : ectodermal dysplasia which affecting the development of teeth,hair , nails and sweat glands .more than 150 syndromes ,inherited by (spontaneous mutations ,AD,AR ,X LD,XLR)
Atobic dermatities

13. Atopic dermatitis
Atopic dermatitis is frequently associated with reduced sweating and pruritus when sweating is triggered. Patients with psoriasis may have similar symptoms, but less frequently. There remains an idiopathic category; this variant may respond to oral steroid treatment. Remission is possible but not universal. 
Anhidrosis with pruritus is a rare syndrome of young adults. Severe itching occurs whenever the person is stimulated to sweat. No sweat is delivered to the skin surface, but when the body temperature is raised by about 0.5°C, fine papules appear at each eccrine orifice.

14. Atopic dermatitis
The associated pruritus is so severe that the patient feels completely incapacitated and distracted. Cooling immediately resolves the symptoms. This may represent one form of tropical asthenia or a mild form of the autonomic neuropathies described later. The natural history is unknown, but spontaneous resolution may occur after several years. These patients are frequently misdiagnosed as having cholinergic urticaria.

15. Treatment
Stay in a cooled environment. This is one of the best ways to avoid the symptoms.
Drink plenty of water or iced drinks to keep yourself hydrated. Sweating too much can quickly dehydrate you.
Wear lightweight cotton fabrics. They allow the air to reach your skin.