Why do you lose hair?

Losing hair is normally a step-by-step process over a long period of time. If the hair loss is caused by a disease, it may happen very quickly.

As we grow older, there is a gradual change to the hair follicle. The hair follicle shrinks and the production of the hair is weakened. Eventually, the hair follicle becomes so shrunken that the hair falls out.

At the same time, the anagen growth phase also shortens with age. The anagen phase is when the hair grows and generally has, when we’re younger, a lifespan between 2–10 years. For older people, this phase is shorter due to the hair follicle not being as strong as it once was, since the hair follicle is shrunken. This means that the lifespan of the hair grows shorter before the hair falls out.

Common causes for hair loss

Hereditary hair loss

The most common cause of hair loss is genetic. However, heredity may skip a few generations, so just because hair loss or baldness runs in the family, this doesn’t necessarily mean that you will be personally affected. Regardless, hereditary hair loss is a natural process, but there are very good chances of treatment if this is started in time.

Here you can read more on hereditary hair loss

Illustration of how hair loss is genetically coded


If you have been under a lot of stress during an extended period of time, suffer from symptoms of exhaustion, or have gone through physical or psychological stress, the body often reacts by shutting down hair production. The hair will however remain on the head, so it is difficult to make the connection to the stressful period. The hair falls off up to 6 months after entering the dormant phase, and then you may lose a lot of hair in a short period of time.

Read more on stress-related hair loss here

Illustration person who is losing hair from stress


Some severe fevers or infections trigger hair loss. One example is dengue. This is classified as a physical stress on the body and the hair loss may occur several months after. The hair will be able to grow back and PRP aids in that process. Hormonal diseases, such as thyroid disorders, may also have a major impact on the hair.

There are also hair diseases that have a direct impact on the hair. The possibly most well-known is alopecia areata, spot baldness. The body’s immune system attacks the hair follicles and the patient goes bald in places. Alopecia areata is not necessarily limited to the head but may present itself in the beard and on other parts of the body.

Read more on hair diseases here

illustration of a person with spot baldness alopecia areata


Certain medicines affect hair growth. Cancer medicine has a strong impact on hair growth. Some cancer treatments knock out everything in the body as they cannot properly tell the difference between cancer cells and healthy cells. Other medicines that may cause hair loss include certain types of antibiotics, anticoagulants, anti-depressants and acne medicines containing vitamin A.

Diet and vitamin deficiency

The diet is always important for all humans. However, relatively few in Sweden suffer from hair loss or thin hair due to a poor diet. Most people eat enough good food in order to not suffer from severe vitamin deficiency, which may cause hair loss. Individuals with eating disorders or extreme diets may, however, be negatively affected, and not just the hair.

The most common vitamin and mineral deficiencies people experience are iron deficiency (anemia), vitamin B deficiency or zinc deficiency, which all affect skin and hair. Iron deficiency is more common in women, but occasionally occurs in men. If you suspect an iron deficiency, we can check this at the clinic and you’ll have an answer within a few days.

Hormonal causes

If the patient suffers a hormonal disturbance, the body can often react by dropping hair. A hormonal disturbance may occur when changing contraceptive pills, during menopause or post pregnancy, which may have an impact on the hair.


Female hair loss usually starts during menopause when the body’s level of estrogen decreases. Estrogen affects many organs in the body and the new hormone levels may impact the growth of the hair. Strictly medicating using estrogen usually won’t make the hair loss reversible.


During pregnancy, many may feel that the hair grows very well and after childbirth, usually in connection with breastfeeding, the hair loss begins. This is because the body produces a lot of hormones during the course of pregnancy and after giving birth, the body attempts to return to normal hormone production. This may take a while, up to a year, and if you get pregnant again during that time, the body often doesn’t have time to recuperate between pregnancies.

Contraceptive pill

Some women lose hair in connection with contraceptive pills. This can often be tied to changing contraceptive pills for pills with another hormone composition than what was previously used.