A New Lung Related Side Effect of Oral Minoxidil: A Hypersensitivity Pneumonitis-Like Presentation

Hypersensitivity Pneumonitis from Oral Minoxidil

Low dose oral minoxidil (LDOM) is increasing used for a variety of different types of treating hair loss. The term LDOM typically refers to doses under 5 mg.

Oral minoxidil is known to have a variety of side effects. Fortunately, many of the potential side effects are not common.  Typical side effects of LDOM include hair on the face,  fluid retention in the face or feet, hair shedding. Less common, but more serious, side effects  including pleural effusions, pericardiac effusions and cardiac tamponade.

Hypersensitivity-pneumonitis like Presentation from Oral Minoxidil

Authors from Japan present a new side effect to know about: hypersensitivity pneumonitis like presentation.

The authors reported the case of a 71 year old male with a type of cancer known as essential thrombocytosis who presented for medical attention with low oxygen saturation, pericardial effusions, and a specific pattern on CT scan of the chest known as ground-glass opacity. What was so remarkable in this patient’s case was that these symptoms resolved extremely well when the patient was admitted to hospital and then started up again when he was discharged back home.  Then entire case was thought to be a condition known as  “hypersensitivity pneumonitis (HP)” until it was discovered by chance that the patient had been hiding the fact that he used minoxidil and

The Full Story

The full story was that the patient had a CT scan in 2021 as part of his cancer care. The patient was diagnosed in the past with a cancer known as essential thrombocytosis. The CT scan showed abnormal findings – specifically these ground glass opacities and other findings suggestive of hypersensitivity pneumonitis ( a type of lung inflammation when people are exposed to an allergen such as a plant protein, animal protein, microorganisms or chemicals).

The patient mentioned he had some mild but gradually worsening shortness of breath on exertion. The patient denied coughing or sputum production and reported an occasional low-grade fever. In addition to the cancer diagnosis ( ET), the patient had a few other medical issues including obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease. The ET cancer had been diagnosed 9 years ago and was managed with aspirin and hydroxyurea (typical treatments for ET). Sleep apnea was diagnosed 3 years prior and the patient used a continuous positive airway pressure therapy (CPAP) mask. He was an ex-smoker with a history of smoking one pack per day for 40 years.

When he was examined by his doctors his oxygen saturation was 93% breathing room air. Chest auscultation revealed scant fine crackles at the base of the lungs. CT imaging findings were consistent with nonfibrotic hypersensitivity pneumonitis.  

The patient’s blood tests showed that interstitial pneumonia markers were moderately elevated, with Krebs von den Lungen-6 (KL-6) at 942 U/mL and surfactant protein D (SP-D) at 117 ng/mL

What was a bit of a surprise was the  the analysis of bronchoalveolar fluid fluid (BALF) showed a near-normal cell count. Normally in HP there is a significant increase in lymphocytes found.  

HOPSITAL ADMISSION 1

Due to these findings the patient was kept in hospital and slowly improved. He really didn’t have much of a change in his treatment plan. Within a few days he had an improvement in breathing. The CT  improved and his breathing tests (spirometry) improved. He was noted to have some elevated antibody tests against bird-related antigens and so his doctors made a tentative diagnosis of hypersensitivity pneumonitis, possibly due to some kind of bird antigen exposure. The doctors felt that the diagnosis was not definite but it was the only thing that seemed to fit.

He was discharged home and told to avoid contact with birds. He had a down filled comforter he enjoyed using and was told to avoid that too.

HOPSITAL ADMISSION 2

10 months later, the patient returned to see his doctors. Again, he had shortness of breath despite the fact he was avoiding birds and not using his down comforter. The CT scalp showed the grounds glass opacity (GGO) appearance again. There was now a pericardial effusion. Echocardiography showed diastolic dysfunction, a moderate amount of pericardial effusion without signs of tamponade, moderately elevated pulmonary artery pressure, and an estimated pulmonary artery systolic pressure (PASP) of 54 mmHg

 He was given some diuretics to deal with the extra fluid around the heart and fortunately things improved again. CT and spirometry showed improvement.

It was still not clear why he was developing this ground glass opacity appearance on CT scan. Normally this appearance is due to some kind of inhaled antigen so the doctors kept searching. It was noted that he was using an air humidifier and CPAP machine so  fungi were suspected to be the culprit. He was discharged with instructions to stop using the humidifier, change the CPAP tubing, and clean the machine really well.

The patient returned home and followed the instructions but again developed the shortness of breath again.

HOPSITAL ADMISSION 3

The patient would come to be readmitted to hospital just one month later. CT scan confirmed the reappearance of GGO and pericardial effusion.

On this particular admission, he brought in two medicines he purchased through an online store for his hair loss: oral minoxidil (which has was using at 10 mg/day) and oral finasteride. He took these medications for hair loss. He had been using them for many years.

He reported to his doctors that he stopped them each time he was admitted to hospital and started them again each time he was discharged from hospital.

All in all, authors of this report suspect that it was the oral minoxidil that caused the lung issues and pericardial effusion. He was advised to stop taking them. His condition improved again with diuretics and hospitalization

Conclusion

This was an interesting case and highlights what appears to the first case of minoxidil- induced lung disease presenting as hypersensitivity pneumonitis-like lung infiltrate. These doses of oral minoxidil (10 mg) are a bit higher than typical at 5 mg, but it’s still an important side effect to know about.

It also highlights that patients do not always tell us the full story and we don’t always ask the full story.

REFERENCE

Takekosh D. Minoxidil-induced lung disease, masquerading as hypersensitivity pneumonitis. Respir Med Case Rep . 2023 Apr 29;43:101861.