How Often to Cut Your Nails: Charaka Samhita Sutrasthana 8.18 on Trih Pakshasya, Five Qualities and Seven CDC Rules

इस लेख को हिंदी में पढ़ें: नाखून कितने दिन में काटें? चरक संहिता 8.18, पाँच गुण और CDC के सात नियम

📖 19 min read · Charaka Samhita, Sutrasthana 8.18-19 and 5.98-99; Bhavaprakasha, Dinacharya 130; US CDC (2024)

Cutting Nails When They Look Long: Today's Habit and the One Thing We Get Wrong

How often should you cut your nails? For most of us the honest answer is: when they look long. The clipper lives in a drawer, comes out every two or three weeks, and goes back. In between, some of us bite or chew a corner that has grown out. Very few of us clean under the nails unless the dirt shows.

Our reel opens with a question: do you cut your nails only when they start to look long? The Charaka Samhita, one of the oldest texts of Ayurveda, answers with a number.

Out of sight, out of mind: in many homes the nail clipper comes out only when the nails already look long.

The thing most of us get wrong is the trigger. We think of nail cutting as a repair: wait for the nails to look long, then fix them. Charaka puts it on a calendar. His rule is not "cut them when they are long" but "three times a fortnight", long or not. And the rule is not about nails alone. It names four things in one breath: the hair of the head, the beard and moustache, the body hair and the nails.

The text also gives reasons. A verse three chapters earlier lists five qualities of cutting and grooming the hair and nails. Our reel named two of them, clean and appearance. This page gives all five, as the text's own words. Then it sets them beside a modern reading from the US CDC, whose short page on nail hygiene ends in seven everyday rules.

Sadvritta: Where the Rule Sits in Charaka Samhita, Sutrasthana 8.18

The rule comes from the eighth chapter of the Charaka Samhita's first section, the Sutrasthana. The chapter is the Indriyopakramaniya Adhyaya, the chapter on the senses (indriya), and it ends with a long code of good conduct, sadvritta. Our overview of the whole chapter is here: Charaka Samhita Part 8: the senses and sadvritta.

Charaka says what the code is for before he lists it. Following it brings two things at once, health (arogya) and mastery of the senses (indriya-vijaya). The CSRTSDC edition's English, which we quote on this page unless we say otherwise, reads maintenance of positive health and control over sense organs. Then comes one very long verse, 8.18, made of short clauses. Many are about character. Two of our earlier pages take single clauses from it: forgiveness and bearing harsh words, and envy the effort, not the result.

The nail clause sits in a small group about the body, near the top of the verse:

Read in order, the group moves from washing to cutting to dressing. Bathe twice a day (dvau kalau upasprishet). Clean the excretory passages (malayana) and the feet often (abhikshnam). Have the hair, beard, body hair and nails cut three times a fortnight. Wear clean clothes, keep the hair (kesha) in the usual style, and oil the head, ears, nose and feet every day. So the nail rule is not a stand-alone tip. It is one step in a routine, daily and fortnightly, of keeping the body clean and presentable.

Trih Pakshasya ... Samharayet: The Clause Word by Word

• Trih (त्रिः): three times.
• Pakshasya (पक्षस्य): of a fortnight. A paksha is a fortnight, about 15 days; in the Indian calendar each lunar month has two, the bright half and the dark half. Together, trih pakshasya means three times a fortnight.
• Kesha (केश): the hair of the head.
• Shmashru (श्मश्रु): the beard and moustache.
• Loma (लोम): body hair.
• Nakha (नख): the nails. The ending of nakhan, at the close of the long compound, makes all four the object of the verb.
• Samharayet (संहारयेत्): should have them taken off. The verb is causative: not only "should cut" but "should have them cut", which covers a barber's work as much as your own.

Samharayet, should have them cut: the rule covers a barber's chair as much as your own scissors.

Two English versions of this clause are easy to find, and both drop one of the four words. The CSRTSDC edition: Cutting of hair, shaving & nail cutting should be done thrice a fortnight. The Charaka Samhita: Handbook on Ayurveda, Vol. I (p.219): cutting hair, shave and nail cutting done 3x/fortnight (14 days?). Hair, shaving, nails: three items. The Sanskrit has four. Body hair (loma) sits in the compound between the beard (shmashru) and the nails (nakha), and neither English line carries it. This page keeps all four, because the text does. The verse says nothing more about body hair, and how a reader applies that word today is a personal matter.

Three times a fortnight, in days

The verse gives a count per fortnight, not a number of days. The days are our arithmetic:

• A fortnight is about 15 days, and 15 ÷ 3 = 5. So three times a fortnight is about once every five days.
• The Handbook's note asks whether a fortnight means 14 days. 14 ÷ 3 is about 4.7, so the answer barely moves: about every five days.
• A 30-day month holds two fortnights, so the rhythm comes to about six trims a month.
• Cutting the nails every two to three weeks comes to about one and a half to two trims a month.

So the gap between the habit and the text is not small: on this arithmetic, Charaka's rhythm (trih pakshasya) is three to four times as frequent as "when they look long". Notice also what the text does not say. It never says "every five days". It says three times a fortnight, and leaves the spacing to the reader.

Charaka's Five Qualities of Cut and Groomed Hair and Nails (Sutrasthana 5.99)

Why cut so often? Sutrasthana 8.18 gives the rule without reasons. The reasons are three chapters earlier, in Sutrasthana 5, the Matrashiteeya Adhyaya. That chapter begins with the right quantity of food and then walks through a daily routine (dinacharya): collyrium for the eyes, oil in the nose, cleaning the teeth and tongue, gargling, oil massage, the bath, clean clothes and more (our overview: Charaka Samhita Part 5, food quantity and the daily routine). Near the end of that routine come two short verses, one about cleaning and one about cutting.

The subject of 5.99 is in its second line: the cutting (kalpana) and the dressing or grooming (samprasadhana) of the hair, beard, nails and the like (kesha-shmashru-nakha-adi). Here too the English versions trim the list: the CSRTSDC line says body hair and nails, and the Handbook's chart (p.209) labels the verse as shaving and hair dressing, with no nails. The Sanskrit names head hair, beard and nails. Its first line gives five words for what this grooming is. Here they are in the text's order, each with the two English editions and a plain meaning. They are Charaka's words, not our promise.

1. Paushtika: nourishing

Paushtika comes from pushti, nourishment, the body filling out. The CSRTSDC English has plumpness; the Handbook has nutritive.

2. Vrishya: for virility

Vrishya is the classical word for what supports virility: virility in the CSRTSDC English, aphrodisiac in the Handbook. It is not special to nails. The same chapter gives the same word to bathing (5.94), to fragrance and garlands (5.96) and to wearing footwear (5.100).

3. Ayushya: for long life

Ayushya means good for the life-span (ayu): longevity in the CSRTSDC English, life-promoter in the Handbook. It is the chapter's most common word of praise. In verses 93 to 102 it goes to seven things: bathing, clean clothes, fragrance and garlands, jewels, cleaning the feet and the excretory passages, grooming the hair and nails, and carrying a walking staff.

4. Shuchi: clean

Shuchi means clean or pure, and both English editions say cleanliness. Of the five, this is the one a modern reader recognises at once, and the first of the two our reel used.

5. Rupa-virajana: it makes the appearance shine

Rupa is form or appearance, and virajana is making it shine. The CSRTSDC English has beauty; the Handbook has beautification. This is the second quality in our reel.

Put side by side, the five words read less like five effects and more like the language this chapter uses to praise a well-kept body. Verse 5.98, just before, praises frequent cleaning of the feet and the excretory passages (pada, mala-marga) the same way: medhya (good for the intellect), pavitra (purifying), ayushya (for long life) and alakshmi-kali-nashana, which the CSRTSDC English gives as dispels misfortunes and sin. The two verses are a pair. Verse 5.98 is about washing and 5.99 about cutting, the same order as the clauses of 8.18, where cleaning the feet comes just before cutting the nails.

A basin, a lota and a towel for washing the feet: the cleaning that verse 5.98 praises, just before the verse on cutting.

The chapter closes this run of verses with an image worth keeping: Like the lord of a city in the affairs of his city, and a charioteer in the management of his chariot, so should a wise man be ever vigilant in the caring of his own body. (Sutrasthana 5.103.)

Pancharatra: The Bhavaprakasha Says It as Every Five Nights

Our arithmetic gave about five days. A much later classical text, the Bhavaprakasha, says it in those terms. In its daily routine (dinacharya, Purva Khanda), in the Hindi-commentary edition we read, verse 130 comes after the verses on collyrium (anjana) and just before the line on never plucking the hairs of the nose:

Three things stand out.

• The interval is in the words. Pancharatra means five nights. Where Charaka gave a count per fortnight (trih pakshasya), the Bhavaprakasha gives the gap, and its gloss reads it as the fifth day. The two agree.
• All four are there. Nails (nakha), beard (shmashru), hair (kesha) and body hair (roma, another form of loma): the same four as Charaka, in a different order. The gloss keeps the causative too: कतरवावे, "have them cut".
• The praise is Charaka's, reworded, with one real change. The next lines echo Sutrasthana 5.99: cutting (kartana, where Charaka has kalpana) and grooming (samprasadhana) are paushtika and ayushya, and bring cleanliness (shaucha, Charaka's shuchi) and lustre (kanti, close to Charaka's rupa-virajana). Those are near-synonyms. The real change: where Charaka has vrishya, the Bhavaprakasha has dhana, wealth.

That swap is a small lesson in how to read such lists. If one classic praises grooming for virility and a later one, in the same slot of the same line, praises it for wealth, both are telling us that grooming was valued, in the words each used for good things. Neither is a measurement. Our page on the Bhavaprakasha's exercise verses walks through the morning order around verse 130: Vyayama in the Bhavaprakasha. The same book also has a view of what nails are: in its chapter on the tissues (dhatu), nails and body hair are a by-product (mala) of bone (asthi). That reading has its own page, Dhatu Mala in the Bhavaprakasha.

The Modern Reading: What the CDC Says About Nails (2024)

The modern side of this page comes from the US Centers for Disease Control and Prevention (CDC). Its page Healthy Habits: Nail Hygiene (16 April 2024) is short, and we read it in full. Its overview opens with two sentences:

The second sentence is the one our reel quoted. It sits well with the CDC's first everyday tip, which is about length: a shorter nail leaves less room underneath. It is a point about hygiene, about where dirt and germs collect.

The CDC's handwashing page, About Handwashing (16 February 2024), brings the nails into every wash. Among its five steps: Lather the backs of your hands, between your fingers, and under your nails. And: Scrub your hands for at least 20 seconds. It even gives a timer: Hum the “Happy Birthday” song from beginning to end twice.

Soap and a nail brush at the basin: the CDC's handwashing steps include lathering under the nails.

Charaka's code of conduct has its own line about hands. In the rules for eating, in the very next verse, Sutrasthana 8.20, one should not eat without washing hands, feet and face. The two do not lean on each other. They arrive at short, clean nails from different places: the text from a routine (sadvritta, dinacharya) of keeping the body clean and well kept, the CDC from where dirt and germs collect. We read them side by side, not as one proving the other.

Seven Everyday Nail-Care Rules (CDC)

The CDC's nail page ends with a short list of everyday tips. Here they are, all seven, in the CDC's own words, each with a plain note.

A clipper and a file laid out after washing: the CDC's third tip is to clean nail tools before use.

1. Keep nails short and trim them often. The CDC gives no number of days. Charaka's three times a fortnight (trih pakshasya) is one way to keep "often".
2. Scrub the underside of nails with soap and water (or a nail brush) every time you wash your hands. Not only when they look dirty: every wash.
3. Clean nail grooming tools (like nail clippers and files) before use. A clipper that lives in a drawer gathers dust, so wash it first.
4. In commercial settings such as nail salons where nail tools are shared among people, sterilize nail grooming tools before use. If you have your nails done at a salon, this is the rule for its tools; samharayet already allows for someone else doing the cutting.
5. Do not bite or chew nails. This one is the CDC's, not Charaka's: the code of conduct has no line on biting nails. More on that below.
6. Do not cut cuticles, as they act as barriers against infection, in the CDC's reasoning. The cuticle is the thin skin at the base of the nail. Leave it alone and clip only the nail.
7. Never rip or bite a hangnail. Instead, clip it with a clean, sanitized nail trimmer. A hangnail is the small torn strip of skin beside a nail. Clip it; do not pull it.

Count them and the seven fall into three groups: three about the nails themselves (short, scrubbed underneath, not bitten), two about the skin around them (cuticles and hangnails) and two about the tools (cleaned at home, sterilized at a salon).

Nails on Charaka's Calendar: A Trim About Every Five Days

Put the text and the CDC together and the practical part is simple. Here is what Charaka's rhythm looks like for nails in a modern month.

Fifteen days, three trims: on plain arithmetic, three times a fortnight is about every fifth day.

The fortnight rhythm in a modern month

Three trims a fortnight is about one trim every five days. In a 30-day month that falls on roughly the 5th, 10th, 15th, 20th, 25th and 30th; any fixed five-day cycle works the same way. The clause puts the hair, beard and body hair (kesha, shmashru, loma) on the same rhythm as the nails. Many people today shave more often than that and visit a barber less often. The verse gives one rhythm for all four and adds nothing else about any of them.

What five days of growth looks like

How much does a nail grow in five days? In a small study of 22 healthy young adults in the US, Yaemsiri and colleagues (2010) report: Average fingernail growth rate was faster than that of toenails (3.47 vs. 1.62 mm/month, P < 0.01). Taking a month as 30 days, our arithmetic gives:

• Fingernails: 3.47 mm a month is about 0.12 mm a day, so about 0.6 mm in five days and about 2.4 mm in three weeks.
• Toenails: 1.62 mm a month is about 0.05 mm a day, so about 0.3 mm in five days and about 1.1 mm in three weeks.

So a five-day trim takes off well under a millimetre, while the "when they look long" habit lets about four times as much build up. These are averages from a small group, and nails grow at different rates in different people; the numbers only show the scale. The CDC's line about long nails and Charaka's rhythm point the same way: keep the nails short by trimming a little, often.

Biting and chewing: the CDC's rule, not Charaka's

Our reel closes on nail-biters: never chew your nails with your teeth. That advice is the CDC's: Do not bite or chew nails. The code of conduct in Sutrasthana 8.18-19 has no line about biting nails, and we will not put one in Charaka's mouth.

What 8.19 does have, in its long list of things not to do, is a run of small, restless habits of the hands and mouth:

Na nakhan vadayet means: do not make the nails sound, do not play on them like an instrument. Today that might be drumming them on a table or clicking them together. Set beside grinding the teeth and scraping the ground, our reading is that the list asks for hands and mouth at rest. Nail biting looks like a habit of the same family, but that resemblance is our observation, not the text's words.

Fingernails and toenails

Nakha covers both, and the verse does not separate them. The feet get their own attention in the same clauses: 8.18 asks for frequent cleaning of the feet, and 5.98 praises it. The CDC's page also speaks of fingernails and toenails alike. Toenails grow more slowly (the 2010 figures above), so they look long later, but the verse gives one rhythm for all nails.

None of this says that cutting your nails every five days will keep anything away from you. It says something more modest. The Charaka Samhita asks for a regular rhythm of cutting and cleaning, and the CDC asks for short, clean nails. A five-day trim keeps both.

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