Minoxidil and the cat

Minoxidil is Toxic to Cats

Minoxidil is FDA approved for treating male and female androgenetic alopecia. It has been studied in humans for over 35 years. 
However, it is not well known among users of minoxidil that minoxidil may have a unique toxicity to cats. That is not to say that cat owners can not use minoxidil - but important lessons come from a 2004 study in the veterinary literature.

DeClementini and colleagues reported 2 cats who died after their owners applied minoxidil to areas of hair loss on the cat. The first cat was a 3 year old cat had just one drop applied to an area of hair loss . That cat had trouble breathing, high heart rate, water in the lungs (pulmonary edema and pleural effusion) and showed increased liver enzymes. The cat died 15 hours later.

The second cat was a 7 year old cat and the owners applied an unknown amount of 5 % minoxidil solution to an area of hair loss and left the home for three days. Upon returning to the home, the owners found the cat also having difficulty breathing. Veterinarians confirmed pulmonary edema and pleural effusions. That cat died 10 hours later despite supportive care.

These are important lessons. Minoxidil must not be applied to cats and cats should not have the opportunity to play with the hair of owners who have applied minoxidil for their own hair loss. Most of what is needed though is just common sense. It is possibly to have a cat and have minoxidil users in the home.

Minoxidil may be uniquely toxic to cats and less toxic to other pets like dogs. A 1997 study involved the application of 3 % minoxidil to hairless puppies (descendants of Mexican hairless dogs) for 31 days. Side effects were not observed. However, minoxidil should never be applied to any animal. 

Reference

Suspected toxicosis after topical administration of minoxidil in 2 cats. Journal of Veterinary Emergency and Critical Care 2004; 14:287-292

Minoxidil: Can it raise heart rate?

Minoxidil can raise heart rate in some individuals

One uncommon side effect from minoxidil is an increase in heart rate. This is not the only thing that minoxidil is doing in this situation. It's actually primary lowering blood pressure and in turn the body increases heart rate to compensate.

I'm often asked if one needs to stop. This needs to be handled on a case by case basis. Some people will say to me " my heart rate goes up when I exercise ... so what's the difference?"

During exercise both heart rate and blood pressure go up. It's a very different physiology than minoxidil. A person's heart rate also goes up (and blood pressure goes down) when hey are dehydrated and we know this is not good.  A person's heart rate can go up (and blood pressure go down) with topical minoxidil. Fortunately, this does not happen to everyone. But if there are significant heart rate changes with minoxidil, I advise checking with one's physician about whether or not to stop. This is especially important for those over 65.

Minoxidil use after ages 65: Should I just go for it?

Minoxidil (Rogaine, etc) is FDA approved for ages 18-65

I'm often asked by patients if they should just give minoxidil a 'try'. Give it a 'go'. I respond that minoxidil can certainly be helpful but minoxidil is certainly not for everyone.

Minoxidil is FDA approved for men and women 18-65 with a type of hair loss known as androgenetic hair loss. If an individual has some other hair loss condition besides androgenetic hair loss (there are actually dozens of other kinds) and if the individual is over 65, they should check with their physician if minoxidil is safe or not.

Minoxidil is not for everyone

I don't prescribe minoxidil if:

1.     the patient has heart problems, especially ischemic type heart disease or certain types of heart failure

2. the patient has heart rhythm issues (like atrial fibrillation)

3. the patient has certain internal conditions (like pheochromocytoma)

4. the individual has allergies to any of the components of minoxidil, such as propylene glycol in minoxidil solution or allergy to the minoxidil itself

 

Final Comments:

Minoxidil has a good safety profile and that has lead to its availability as an over the counter product.  But minoxidil is not for everyone. An 82 year old patient with heart failure and two previous heart attacks is not a candidate for minoxidil. A patient with hair loss due to dissecting cellulitis of the scalp (a different condition than genetic hair loss), will likely find little to no use from minoxidil application. Minoxidil is not for everyone.

Minoxidil - Does it help with hair loss ... in the front ... or top .. or both?

Accumulating evidence suggests minoxidil helps with hair loss in the crown (top) but may help hair loss in the front and temples in men as well.

Minoxidil - Does it help with hair loss in the front?

Minoxidil is a topical medication that is FDA approved for treating genetic hair loss (sometimes referred to as androgenetic alopecia). If you pick up a bottle of minoxidil it will state that it is to be used for hair loss in the crown in men and may not benefit other areas of hair loss. The original studies of minoxidil focused on the crown and did not address the benefit in the front of the scalp.

So the question that remains is:  

Does minoxidil help men with hair loss in the front of the scalp or not?

Certainly, the answer is yes.   Many hair loss specialists around the world, including myself,  have witnessed benefit to minoxidil in the front of the scalp in balding men.  However, the companies which produce minoxidil are not setting out to formally prove the benefit in the front of the scalp and are not seeking approval from health regulatory authorities to be able to change the labelling on the bottles to indicate that it "works in the front and back."

New study shows 5 % minoxidil benefits men with hair loss in the temples

Back in the month of May 2013, I attended the World Congress of Hair Research in Edinburgh Scotland. A really nice study was presented by Dr. Blume Peytavi and colleagues from Berlin, Germany. They studied 70 men with moderate genetic hair loss and studied whether minoxidil 5 % foam could help hair loss in the crown and in the front.  The German group showed that men using minoxidil 5 % foam did obtain benefit from using the medication in the front and in the crown.  This was one of the very first studies showing the minoxidil foam benefits hair loss in the front.

Conclusion: 

Minoxidil has long been known to benefit men with hair loss in the crown. Accumulating evidence suggests it also benefits men with hair loss in the front (temples). More studies are needed to determine just 'how much' it helps men with hair loss in the front. In general, minoxidil seems to work better in the earliest stages of hair loss - as hairs are thinning and miniaturizing. 

Reference

Hillman K, Bartels GN, Stroux A, Canfield D, and Blume-Peytavi U. Investigator-initiated double blind, two-armed, placebo-controlled, randomized clinical trial with an open -label extension phase, to investigate efficacy of 5 % Minoxidil topical foam twice daily in men with androgenetic alopecia in the fronto-temporal and vertex region concerning hair volume over 24/52 weeks.  Poster at: World Congress of Hair Research, Edinburgh Scotland May 2013.

Benefits of Combining Minoxidil and Finasteride

Benefits of Combining Minoxidil and Finasteride

Minoxidil and Finasteride are two FDA approved treatments for hair loss. Minoxidil is a topical solution that is rubbed on the scalp and finasteride is an oral treatment (pills). Many men with genetic hair loss (androgenetic alopecia) consider the use of these medications and may consider hair restoration as a more permanent solution.

Both minoxidil and finasteride have their own set of side effects. Finasteride, however, is much more effective. GIven that these two agents are clinically proven to help with hair loss, I'm often asked - "Is it better to use both of these products or should I just pick one?"

Combination Minoxidil and Finasteride better than single treatment

The answer is - 'yes.' There is clinical evidence that men using finasteride for hair loss who add minoxidil to their treatment plan have a slightly better result than men who only use finasteride. The benefits, however, are small. It makes sense that the two medications act synergisticially in treating hair loss given that they act differently. Minoxidil helps hair growth by directly stimulating the hair follicle. In contrast, finasteride works by blocking the action of the potent male hormone dihydrotestosterone or "DHT". 

Conclusion

Both minoxidil and finasteride should be considered. For men with early hair loss, the use of both might help and may be considered prior to a hair transplant. Minoxidil and finasteride have less benefit for men with advanced hair loss. In these cases, a hair transplant is the primary treatment.

This blog has been filed into the following folders:

Hair Loss Drugs and Breastfeeding: Which Medications are Safe?

The following situations are a commonly encountered in a busy hair loss practice:

A 32 year old woman with genetic hair loss (androgenetic alopecia) was using topical minoxidil solution before her pregnancy. She stopped it during her pregnancy and now is wondering if she should start it up again after her delivery. She is breastfeeding. Is it safe to use this medication?

A 28 year old woman with genetic hair loss (androgenetic alopecia) was using the oral drug Spironolactone  before her pregnancy. She stopped it during her pregnancy and now is wondering if she should start it up again after her delivery. She is breastfeeding. Is it safe to use this medication?

 A 34 year old woman with discoid lupus of the scalp (a scarring alopecia) was using the oral drug Hydroxychloroquine before her pregnancy. She stopped it during her pregnancy and now is wondering if she should start it up again after her delivery. She is breastfeeding. Is it safe to use this medication?

 A 27 year old woman with folliculitis decalvans of the scalp (a scarring alopecia) was using the oral drug clindamycin along with the drug rifampin before her pregnancy. She stopped it during her pregnancy and now is wondering if she should start it up again after her delivery. She is breastfeeding. Is it safe to use this medication?

WHICH HAIR LOSS MEDICATIONS ARE SAFE TO USE WHILE BREASTFEEDING?

Although I often discontinue many hair loss medications during pregnancy, the question frequently arises as to whether some medications can be restarted while moms are breastfeeding.  Breastfeeding has many benefits for babies.  For some drugs, the answer is yes. For others, the answer is no.

In 2001, the American Academy of Pediatrics published a helpful guide as to the safety of medications during breastfeeding. It's important to always check with your physician before starting any medication during breastfeeding. However, the following medications (used in hair loss) are felt to be safe for women who are breastfeeding.  For a full list of medications which are safe during breastfeeding, click here.

List of Hair Loss Drugs Regarded as Safe in Breastfeeding

B12

Cefazolin

Chloroquine

Ciprofloxacin

Clindamycin

Hydroxychloroquine

Folic acid

Ketoconazole

Topical Minoxidil

Prednisone

Rifampin

Trimethoprim/sulfamethoxazole

Therefore, the four women I mentioned above were able to safely use these medications while breastfeeding.  However, women considering using any medication while breastfeeding must check with their health care provider.

Minoxidil and Itch: Am I allergic to Minoxidil?

Some individuals who use minoxidil solution develop itching in the scalp.  In most cases, this is not due to an allergy to the minoxidil but rather due to irritation from a chemical that is mixed with the minoxidil. This chemical is called propylene glycol. If patients have a lot of itching with minoxidil, a minoxidil formulation that does not contain propylene glycol can be recommended.  A common example of a proplylene glycol free product would be minoxidil 5% foam or minoxidil compounded by the pharmacist in glycerin, water and ethanol.

Very rarely, a patient can be truly allergic to minoxidil. Specialized allergy testing performed by a dermatologist (called patch testing) can help to determine if a patient is actually allergic to minoxidil.  Usually such testing is only performed in complex or challenging situations.

What's New in the World of Hair Research? Minoxidil.

5 % Minoxidil Foam vs. 2 % Minoxidil Solution

Minoxidil 2 % topical solution is approved for the treatment of androgenetic alopecia in women.   It is typically used twice daily. Although Minoxidil 5 % is formally approved for use only in men, it may also be recommended for women in some situations. 

Researchers from Germany and the United States set out to compare if once daily use of 5 % topical minoxidil foam formulation was just as good as twice daily 2 % minoxidil solution.

To test this, 113 women with androgenetic alopecia randomonly assigned to receive wither 5 % minoxidil foam (once daily) or 2 % minoxidil solution (twice daily) over a period of 24 weeks.

After 24 weeks of the study, researchers showed that once daily 5 % minoxidil foam was just as good as twice daily 2 % minoxidil solution.  Both formulations were able to increase hair counts and hair thickness in a similar proportion of women.  Women in the study actually preferred the 5 % foam over the solution reported that the foam was less likely to interfere with hair styling and less like to cause itch and dandruff. 

Reference:  Blume-Peytavi et al. A randomized, single-blind trial of 5% minoxidil foam  once daily versus 2% minoxidil solution twice daily in the treatment of androgenetic alopecia in women. J Am Acad Dermatol 2011.