Hello, Thank you for writing to us,

Feeling sick, shaking and shivering, increased heart rate (tachycardia), these symptoms describe that you have had episodes of chills and rigor. Chills and rigors are usually the first sign of infection, specifically bacterial. More over it is common in women with urinary tract infection.  Unlike in a healthy young man (details like age, sex, past medical history and family history not mentioned) it could be any other infection.

I would like to give you some of the causes of rigor in brief:

1)Infections: This is the most common cause of shaking and shivering along with increased heart rate. Firstly I would like to describe about the temperature regulating mechanism by the body. The human body is always maintained at a particular temperature (98.4 degree F) which is regulated by a structure in the brain called hypothalamus. When the bacteria in the blood increase in number, they release substances called pyrogens. These pyrogens raise the temperature set point which causes the body to respond through fever. In order to maintain this temperature, the muscles contract and relax rapidly giving rigors. During this time the heart beats very fast to supply the blood to the peripheral organs.

The following are the infections that are more likely encountered:

a)Ascending  Urinary tract infection leading to Pyelonephritis (reaching kidney)

b)Chest infections

c)Gastroenteritis (food poisoning)

2)Heat exposure: Any occupational exposure to heat for a long time can lead to heat rigors. Such as Heavy machineries, Engine rooms.

3)Drug induced: Medications such as anti-psychotics on long term or over dosage. For example Neuroleptic malignant syndrome, serotonin syndrome

4)After Withdrawl of some drugs like Heroin

5)In the course of treatment: In the course of treatment of some bacterial infection their destruction releases chemical substances causing to increase the temperature set point. This is called Jarish Herxheimer reaction. Seen during the treatment with antibiotics like penicillin in syphilis. Also seen in infections caused by organisms like Bartonella henslae (cat scratch disease), Borrelia burgdorferi (Lyme disease) etc.

Wet sponging could be of great help to the body. Drugs like Parecetamol or Aspirin (anti-pyretic) reduces the temperature. Eventually the rest of the symptoms including rigors and increased heart rate would also subside. If the problem persists despite of these remedies, it is advised to consult a physician for further management.

Hope this helps.