Key takeaways
- Most sudden shedding (telogen effluvium) is temporary and regrows without treatment once the trigger has passed.
- Pattern hair loss works by slowly shrinking follicles. A shrunken follicle can often be coaxed back. A follicle that has stopped producing hair for years usually cannot.
- My working rule of thumb: hair you lost in the last three or four years can often come back; hair that was always thin cannot be changed.
- Medicines work only while you use them, and none works for everyone.
- A proper diagnosis comes first, because the cause decides whether waiting, treatment or surgery makes sense.
Why does the cause matter so much?
This is the question behind almost every hair consultation I do: "Doctor, will it come back?" My honest answer is always, "It depends. Let's find out why it went." Because "hair fall" is a symptom, not a diagnosis. Two people can lose the same amount of hair for completely different reasons, and the answer is different for each.
| Type of hair loss | Does it usually come back? | What decides it |
|---|---|---|
| Sudden shedding after fever, illness, surgery, crash dieting or stress (telogen effluvium) | Usually yes, on its own | Removing or recovering from the trigger; correcting iron, thyroid or B12 problems |
| Hair fall after pregnancy | Usually yes, by the child's first birthday | Time, and checking thyroid and iron if it continues |
| Patchy, coin-shaped bald spots (alopecia areata) | Often, sometimes without treatment | The pattern and extent; this needs a doctor's assessment |
| Male or female pattern thinning (androgenetic alopecia) | Partly, if treated early | How long the follicles have been shrinking |
| Scarring hair loss | Usually not | Early diagnosis to stop further damage |
The NHS describes illness, stress, weight loss and iron deficiency as causes of temporary hair loss, and male and female pattern baldness as the causes that tend to continue. That distinction is where every hair diagnosis starts.
What happens to a follicle in pattern hair loss?
See, what happens is this. Each hair grows from a follicle that runs in cycles: a long growing phase that lasts years, a short transition, then a resting phase of about three months before the hair sheds and a new one starts. In pattern hair loss, hormones called androgens (mainly dihydrotestosterone, or DHT) act on genetically sensitive follicles and shorten the growing phase. Over many cycles the follicle gets smaller and produces a thinner, shorter, lighter hair. We call this miniaturisation.
Scalp hairs grow in little tufts of three or four. In pattern hair loss, these tufts lose hairs one by one, and bald scalp appears only when the whole tuft has gone. That is why you may notice your scalp through your hair long before you see a bald patch.
A miniaturised follicle is still alive and still making some hair, however fine. That is the window where treatment can help. Once a follicle has produced nothing for a long time, medicines have very little left to work on.
What is the 5-year window?
I explain it to people like this: "If you're born with hair which is thin, it cannot change. If you have lost hair in the last three, four years, that can come back."
I want to be clear that this is a clinical rule of thumb from years of consultations, not a fixed scientific cut-off. Some people respond after longer. Some do not respond even early. But it captures something the research supports. The American Academy of Dermatology notes that treatment for pattern hair loss works best when started soon after you notice it, and the StatPearls review describes the condition as chronic and progressive, with early intervention helping to slow it.
Signs that you may still be inside the window: - You can clearly remember your hair being thicker in recent years, or old photos show it. - The thinning area still has short, fine hairs, not smooth, shiny skin. - The change has been gradual over a few years, not decades. - Your parting has widened or your crown has thinned, but the scalp is not fully bare.
Signs that medicines alone may not be enough: - The area has looked the same, smooth and bare, for many years. - Under magnification, no hairs at all are visible in the area.
What can treatment realistically do?
Honest expectations prevent disappointment, so let me be clear. It's about results, and I would rather you know the realistic ones.
- Slowing loss is the first goal. In men, the American Academy of Dermatology reports that finasteride, a prescription tablet, slows further hair loss in about 80 to 90% of men who take it, with results showing in about six months.
- Regrowth is possible but partial. Topical minoxidil can take six to twelve months to show results, and full regrowth is unlikely.
- Results last only while you continue. The NHS states that no treatment is 100% effective, and that finasteride and minoxidil only work while you keep using them.
- Combining approaches often helps. An Indian review in the Indian Journal of Dermatology, Venereology and Leprology notes that minoxidil and finasteride together were reported to work better than either alone, and that treatment is generally long term.
All of these are prescription decisions made after assessment. Finasteride, for example, is not used by women who are or may become pregnant, and it can have side effects that need discussion before starting. Read more in my guides to minoxidil and oral treatments for male hair loss.
What about hair loss after illness?
This is the good news category. After a high fever, dengue, typhoid, COVID or major surgery, many follicles switch into the resting phase together. Two to four months later they shed together, which can feel alarming. DermNet notes that this shedding usually settles over six to nine months and regrowth follows once the trigger is removed. The American Academy of Dermatology reports that after COVID most people see full regrowth within six to eight months of the shedding starting.
In my experience, hair loss after an illness often responds well. The exception is when the illness unmasks underlying pattern thinning, which is common if you have a family history. That is very important to understand, because the shedding settles but the pattern does not, and the pattern needs its own plan. My article on hair fall after dengue, typhoid or COVID covers this in detail.
Is a transplant the answer if hair won't come back?
For areas that are truly bare, a transplant moves hair from the back of the scalp to the thin area. If you tell me you want one, I'll say, "Sure, let's look at it properly." But my view is that a transplant without saving the existing hair "is a bad idea", because the hair around the transplanted area can keep thinning. Transplants must be performed by a qualified surgeon. Read hair transplant or treatment first before deciding.
How we approach this at Dr Tvacha
At our centres in Thane, Andheri, Bandra and Dahisar, the first step is a Rs 499 hair diagnosis to find the cause and check how much of your hair is still in the window. If you need treatment, the 5-Year Time Machine Hair Plan combines monthly in-clinic sessions with home medicines over four months, and the fee is given in writing before you pay. If a transplant is the better route, it is quoted in writing with a named qualified surgeon. Then it is your call. You can read about the plan on our hair page or find a centre near you.
Frequently asked questions
Can hair grow back on a completely bald area?
Usually not with medicines alone. If the scalp has been smooth and shiny for many years, the follicles have generally stopped producing hair, and treatments like minoxidil have little to act on. A transplant may be an option if you have enough donor hair at the back of the scalp. Under magnification, I can check whether any fine hairs are still present.
How long does it take for hair to grow back after shedding?
After a trigger such as a fever or childbirth, shedding usually begins two to four months later and settles over the following months. New growth is short at first, because hair grows slowly. Most people see their volume return over six to twelve months, though full length takes longer. If shedding lasts beyond six months, get checked for other causes.
Does hair grow back thicker if I shave my head?
No. Shaving cuts the hair at the surface and does not touch the follicle under the skin, so it cannot change thickness or the number of hairs. Regrowing hair can feel coarse because the cut tip is blunt, which is where the myth comes from. Shaving is harmless, and some men look very good with it, but it is not a treatment.
Is it too late to treat hair loss in my 40s?
Not necessarily. What matters more than age is how long the thinning has been happening and whether fine hairs are still present. A man of 45 whose crown thinned over the last three years may respond better than a man of 28 whose hairline has been gone since school. A diagnosis gives a much clearer answer than your age alone.
Will my hair fall again if I stop treatment?
In pattern hair loss, yes, gradually. The NHS notes that the main medicines only work while you use them, and the American Academy of Dermatology says hair loss returns after stopping finasteride. Shedding from illness or childbirth is different: once it has recovered, it does not need ongoing treatment. Normally I build a maintenance stage into the plan from the start.
Written by
Dr Amit KarkhanisAesthetic Physician · MBBS, Dip. Dermatology (UK) · Reg. No. 2001/02/1124Founder of Dr Tvacha, practising in Thane since 2005. Leads the weight loss and hair programmes.
Sources
- Hair loss (NHS)
- What is male pattern hair loss, and can it be treated? (American Academy of Dermatology)
- Androgenetic Alopecia (StatPearls, NCBI Bookshelf)
- Telogen effluvium (DermNet)
- Can COVID-19 cause hair loss? (American Academy of Dermatology)
- Androgenetic alopecia: An update (Indian Journal of Dermatology, Venereology and Leprology)
This article is for general education and does not replace a consultation. Medicines and treatments are prescribed only after a doctor's assessment. Last reviewed 25 October 2026.