Medications That Cause Hair Loss

It is totally normal to lose 50-150 hairs a day. But sometimes, with use of certain drugs you may see a lot more hair loss than the usual. If you are able to rule out all other possible causes of hair loss, then it is completely reasonable for you to blame your medication.

The good news is that the drug induced alopecia is usually reversible upon withdrawal of the drug. Hair regrowth occurs after a delay of 3-6 months in most cases.

It is, however, important to note that no amount of hair loss should promt you to change your medication on your own. It is life-risking and should be done only on the advise of your doctor.

How do Drugs Cause Hair Loss?

Drugs are known to cause two types of hair loss: Analgen effluvium and Telogen effluvium.

To understand how drugs can cause hair loss it is important to understand the growth cycle of hair. A normal hair growth cycle consists of three phases:

1. Anagen

It is called as the active growth phase. In this phase, the matrix cells in the hair bulb will show high dividing activity and produces a hair shaft from which a new hair grows later. This period lasts for like 3-5 years. Interestingly, the duration of this phase determines the length of a person's hair.

2. Catagen

It is the transition phase. The lower segments of a hair follicle diminishes and the hair nutrient vessels disconnect. As no more nutrition is given to the hair, the growth of the hair stops. This phase lasts for 10-12 days.

3. Telogen

This is called as the resting phase. Since the hair is without nourishment it eventually dies and falls out. This occurs in about 3 months period. After telogen ends, the follicle reenters anagen phase and a new hair growth cycle begins.

Anagen effluvium

Anagen effluvium is seen almost exclusively with anticancer drugs. Since these drugs attack the cancer cells that are rapidly dividing, they may also attack other body cells in their dividing phase like the hair matrix cells in the anagen phase.

You see the anagen phase lasts for years and so it is obvious that 90% of the scalp hairs at any given time are in the anagen phase. Drug-induced hair loss by anagen effluvium is copious and alopecia in such people is quite obvious. Hair shedding may be noticed in most of the scalp hair, eyebrows, and eye lashes.

Telogen effluvium

This is the most common form of hair loss caused by drugs. Drugs can induce telogen effluvium by one of the three mechanisms :

• By making the premature follicle to enter the resting phase.
• When the drugs that prolong the anagen phase are discontinued. For example, oral contraceptives.
• By premature detachment of club hair in the telogen phase with shortening the telogen phase.

Here, I mention a list of generic names of drugs that can directly affect your hair volume. If you are not sure of the generic name of your drug check on the label or simply google it. For example, the generic name of Accutane (acne medication) is isotretinoin.

Chemotherapy impairs the mitotic activity or simply the dividing capability of the hair follicles. Since chemotherapy is intended to target your body's rapidly dividing cancer cells, other rapidly dividing cells of your body like hair follicles in their growing phase (anagen) also fall prey to these drugs. Within 1-3 weeks of the chemotherapy approximately 90% of the hairs can fall out while still in the anagen phase.

Vitamin A and its derivatives (retinoids) are directly involved in the maintenance of skin and hair. Their toxicity leading to hair loss is also a consistent finding. The mechanism for this type of hair loss appears to be the shortening of normal telogen phase taht result in premature detachment of club hair from the follicles.

Acne medication

• Isotretinoin (Accutane)

Other Retinoids

• Acitretin
• Tretinoin
• Bexarotene
• Tazarotene
• Adapalene

From warfarin and heparin to direct oral anticoagulants, all forms of the anticoagulants have been reported to cause hair loss. The mechanism of hair loss due to these drugs is unknown but the timing of the hair loss with all these drugs strongly suggests a problem in the telogen phase. The hair loss due to anticoagulant tends to be more apparent in women.

The following time link between the drugs and hair loss was shown in various published reports

• Warfarin was taken for 3 weeks, 2 months or even upto 13 years before reporting the effect.
• For heparin it was 2 months.
• Dalteparin induced hair loss was reportd after a use for 3 months.
• Acenocoumarol was used for 3 and 16 months as reported in 2 cases.
• Enoxaparin was reported after 3 months from treatment start.

Female hormones (estrogen and progesterone) and male hormones (androgens- present in minute amounts) are normally maintained in a delicate balance in women. When this balance is disturbed due to normal physiological effects such as menopause and pregnancy, it can negatively effect the hair growth.

Hair is lost after 2-3 months of discontinuation of oral contraceptives. The effect is related to prolongation of anagen phase, with increased estrogen levels. Using low dose estrogen contraceptives seem to reduce the hair loss.

The American Hair Loss Association describes the role of testosterone and its product dihydrotestosterone in hair loss in both men and women. It also provides a list of low and high- androgen index contraceptives.

Hormones and Related drugs Include:

• Birth Control Pills
• Hormone-replacement therapy (HRT) for women
• Male androgenic hormones and all forms of testosterone
• Sterile medroxy progestrone acetate suspension

Cholesterol is important for the production of normal epidermal structure like hair. Agents that lower cholesterol can negatively effect the formation of these structures. Agents that can block cholesterol synthesis can disrupt keratinization process of a hair which can lead to weakening and hair fall.

• Atorvastatin, simvastatin, rarely cause hair loss and it is even more rare with fulvastatin and rosuvastatin.
• Gemfibrozil, bezafibrate also rarely ause hair loss.
• Clofibrate is occasionally found to cause hair loss

Colchicine has antimitotic activity like that of cancer drugs and can cause hair loss in 1-10% of patients taking the drug. According to a report, hair loss due to colchicine occurred after 2 months of colchicine use. The effect seems to be presistent for 1-3 months and thereafter reversible even if the drug is continued.

Allopurinol can cause hair loss by tellogen effluvium.

Antidepressant medications can cause all forms of side effects to hair, ranging from mild hair loss to total alopecia.

A study shows that the risk of hair loss is more with bupropion and least with paroxetine.

• Valproate Sodium

Hair loss and curly hair are occasional side effects of valproate sodium. Like many other drug induced hair loss, it is reversible with sodium valproate.

• Carbamazepine

Carbamazepine rarely causes hair loss.

Several antihypertensive agents cause hair loss but the effect is reversible once the drug is terminated. They seem to have a direct cytotoxic effct on the follicles.

Captopril causes hair loss by decreasing zinc levels. It binds woth zinc to form a complex. Low zinc levels can cause hair loss.

Others include beta-blockers and ACE inhibitors:

• Atenolol
• Metoprolol
• Nadolol
• Perindopril
• Lisinopril

For arthritis, patients are prescribed NSAIDs or DMARDs some of which cause hair loss.

• NSAIDs: NSAIDs are prescribed to lower the inflammation and reduced related pain in the joints. Naproxen, indomethacin, and sulindac cause hair loss but less frequently compared to other arthritis medications.
• DMARDs: These include Methotrexate and Leflunomide. Methotrexate is also used as a chemotherapy drug. It has shown hair loss in 1-3% patients. Leflunomide is used for rheumatoid and psoriatic arthritis. It can also cause hair loss.
• 2.5% patients receiving Auranofin develop alopecia.

Hair loss with antitubercular medication is rare. The following three drugs have been reported so far.

• Isoniazid
• Ethionamide
• Thiacetazone

Antithyroid Drugs

These drugs may csuse tellogen effluvium. The hair appear dry and brittle. The medications include iodine, methylthiouracil, propylthiouracil, and carbimazole.

Antiarrhythmic drugs

Amiodarone and sotalol rarely cause hair loss.

Antimalarial

Hydroxychloroquine can cause hair loss and hair color change in patients.

Parkinson's drugs

Hair loss is one among many dermatological side effects produced by levodopa, a drug used in parkinson's disease.

Bipolar I disorder mefication

Hair loss is a possible adverse effect of lithium carbonate and may appear after weeks to years of therapy.

Chemotherapeutic agents and other drugs can cause hair loss by different mechanisms, most common of which are telogen effluvium and anagen effluvium. By taking a proper history of your hair loss and with physical examination your doctor can clearly tell you if a suspected medication is really the cause and may give you appropriate treatment for it.

If you have had such experience in the past, kindly leave a comment below. This will help our other readers become aware of such reactions and know what to expect from them.

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