Sherry Haynes is currently pursuing a PharmD degree and has experience in both the clinical and management sides of pharmacy.

It is normal to lose 50-150 hairs a day. But sometimes, with the use of certain drugs, you may see a lot more hair loss than the usual. If you can 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 alopecia caused by medication is usually reversible upon withdrawal of the drug. Hair starts to grow again after a delay of 3-6 months in most cases.

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

How do Drugs Cause Hair Loss?

Drugs 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. Normally, growth of hair occurs in three phases:

1. Anagen

It is called the active growth phase. In this, the matrix cells in the hair bulb show high dividing activity and produce a hair shaft from which a new hair grows later. This period lasts for like 3-5 years. Note that 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 diminish 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 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.

The anagen phase lasts for years and this is why 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 eyelashes.

1. Anti-Cancer Drugs

Chemotherapy impairs the mitotic activity (the dividing capability) of the hair follicles.

The therapy is intended to target your body's rapidly dividing cancer cells. In this process, the other rapidly dividing cells of your body like hair follicles in their growing phase (anagen) also fall prey to these drugs. Ninety per cent of the hairs while still in the anagen phase can fall out within 1-3 weeks of the chemotherapy approximately

2. Acne Medication and Other Retinoids

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 the normal telogen phase. This result in premature detachment of club hair from the follicles.

Acne medication

• Isotretinoin (Accutane)

Other Retinoids

• Acitretin
• Tretinoin
• Bexarotene
• Tazarotene
• Adapalene

3. 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.

4. Hormones, Related drugs, Contraceptives

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 affect hair growth.

Hair is lost after 2-3 months of discontinuation of oral contraceptives. The effect is related to prolongation of the 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

5. Cholesterol Lowering Agents

Cholesterol is important for the production of normal epidermal structure like hair. Agents that lower cholesterol can negatively affect the formation of these structures.

Medications that can block cholesterol synthesis can disrupt the keratinization process of a hair which can lead to weakening and hair fall.

• Atorvastatin, simvastatin, rarely cause hair loss and it is even rarer with fluvastatin and rosuvastatin.
• Gemfibrozil, bezafibrate also rarely cause hair loss.

• Clofibrate is occasionally found to cause hair loss

6. Gout Medications

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 is another medication for gout. It can cause hair loss by tellogen effluvium.

7. Depression Medications

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

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

8. Drugs for Seizures/ Epilepsy/ Convulsions

• Valproate Sodium

Hair loss and curly hair are occasional side effects of valproate sodium. But this effect is reversible after a certain period of time.

• Carbamazepine

Carbamazepine rarely causes hair loss.

9. Blood Pressure Lowering Medications

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

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

Others include beta-blockers and ACE inhibitors:

• Atenolol
• Metoprolol
• Nadolol
• Perindopril
• Lisinopril

10. Arthritis Medications

Among the drugs prescribed to arthritis patients, some of the NSAIDs or DMARDs cause hair loss.

• NSAIDs: NSAIDs are prescribed to lower the inflammation and reduce 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 per cent of patients. Leflunomide is used for rheumatoid and psoriatic arthritis. It can also cause hair loss.
• 2.5 per cent of patients receiving Auranofin develop alopecia.

11. Tuberculosis Medication

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

• Isoniazid
• Ethionamide
• Thiacetazone

12. Other Category of Medications

These drugs may cause telogen effluvium. The hair appears 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 colour change in patients.

Parkinson's drugs

Levodopa is a drug used in Parkinson's disease. Hair loss is one of the many dermatological side effects produced by this medication.

Bipolar I disorder medication

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

Other Possibe Reasons for Hair Loss

Conclusion

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.

References

1. Trueb, R.M. (2009). Chemotherapy-Induced Alopecia. Seminars in Cutaneous Medicine and Surgery. 28. 11-14. Retrieved on : 24 July, 2019
2. Rossi, A., Fortuna, M. C., Caro, G., Pranteda, G., Garelli, V., Pompili, U., & Carlesimo, M. (2017). Chemotherapy-induced alopecia management: Clinical experience and practical advice. Journal of cosmetic dermatology, 16(4), 537–541. Retrieved on: 22 July, 2019.
3. Everts H. B. (2012). Endogenous retinoids in the hair follicle and sebaceous gland. Biochimica et biophysica acta, 1821(1), 222–229. Retrieved on: 24 July, 2019
4. Duncan, F. J., Silva, K. A., Johnson, C. J., King, B. L., Szatkiewicz, J. P., Kamdar, S. Pet al., Everts, H. B. (2013). Endogenous retinoids in the pathogenesis of alopecia areata. The Journal of investigative dermatology, 133(2), 334–343. Retrieved on : 24 July, 2019
5. Lesiak K., Bartlett J.R., Frieling G.W. (2015) Drug-Induced Alopecia. In: Hall J., Hall B. (eds) Cutaneous Drug Eruptions. Springer, London. Retrieved on : 24 July, 2019
6. Watras, M. M., Patel, J. P., & Arya, R. (2016). Traditional Anticoagulants and Hair Loss: A Role for Direct Oral Anticoagulants? A Review of the Literature. Drugs - real world outcomes, 3(1), 1–6. Retrieved on : 24 July, 2019
7. Ranugha P, Betkerur JB. (2018). Antihypertensives in dermatology Part I - Uses of antihypertensives in dermatology. Indian J Dermatol Venereol Leprol 84: 6-15 Retrieved on : 24 July, 2019
8. Bougea, A., Spantideas, N., Katoulis, A. et al.(2019). Levodopa-induced skin disorders in patients with Parkinson disease: a systematic literature review approach. Acta Neurologica Belgica; 1-12.Retrieved on: 24 July, 2019.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2019 Sherry Haynes

Comments

Audrey Hunt from Idyllwild Ca. on July 27, 2019:

Thanks for this informative article. I'm grateful not to be on any of these medications. I need every hair on my head!

Liz Westwood from UK on July 25, 2019:

This is an interesting article for reference. Everyone thinks of chemotherapy drugs, but you mention other drugs that can cause hair loss as well.