Overview
Cladosporium is a genus of dark-pigmented molds that are almost impossible to avoid. The species are ubiquitous, saprobic fungi: they live on dead and decaying plant material, and their spores drift through outdoor air and into homes.[1] Most people breathe Cladosporium spores every day without any effect.
Its health relevance is mainly allergic. Cladosporium is one of several airborne molds, along with Alternaria, Aspergillus, and Penicillium, that are linked to asthma severity in people who are sensitized to fungi.[2] Infection is uncommon: researchers describe Cladosporium as only infrequently associated with human and animal opportunistic infections.[1]
Classification
- Phylum: Ascomycota
- Family: Cladosporiaceae
- Genus: Cladosporium
The genus has a tangled naming history. A major 2012 monograph reviewed 993 names that had been assigned to Cladosporium in the broad sense and recognized 169 as true Cladosporium species. The rest were doubtful or were moved to other genera.[3] True Cladosporium species are distinguished by the microscopic structure of the scars where their spores form, with DNA barcodes now supporting species identification.[3]
Species names that commonly appear on mold inspection reports include C. cladosporioides, C. herbarum, and C. sphaerospermum.
Where Cladosporium Is Found
Outdoors, Cladosporium grows on leaves and decaying plant material, and its spores are carried on the air.
Indoors, spores arrive through doors, windows, and ventilation. The mold can also colonize damp building materials. In a study of more than 5,300 samples from materials with visible fungal growth, Cladosporium herbarum was associated with wood and plywood, alongside fungi such as Aureobasidium pullulans and Trichoderma.[4] In practice, it often shows up as dark spotting on window frames, sills, and other surfaces where condensation collects.
Health Significance
Allergy and asthma
The best-documented health effect of Cladosporium is on the airways of sensitized people. A detailed review found a close association between fungal sensitization and asthma severity, involving many airborne fungi including Cladosporium, with exposure indoors, outdoors, or both. Whether the relationship is causal has not been confirmed. The authors proposed the term "severe asthma with fungal sensitisation" for this group of patients.[2]
Cladosporium also appears in research on thunderstorm asthma. After a 2002 thunderstorm in the United Kingdom triggered a wave of asthma admissions, researchers found that the storm was associated with increased airborne levels of Alternaria, Cladosporium, and Didymella spores. Sensitization to Alternaria, Cladosporium, or both was very strongly associated with storm-related asthma (odds ratio 63.97, though with a very wide confidence interval of 3.58–1143.9 because the study was small).[5]
Infection
Cladosporium infections are uncommon. A study of 92 Cladosporium isolates recovered from clinical samples in the United States found:[1]
| Finding | Result |
|---|---|
| Most common species | C. halotolerans (14.8%), C. tenuissimum (10.2%), C. subuliforme (5.7%), C. pseudocladosporioides (4.5%) |
| Isolates matching no known species | 39.8%, representing at least 17 new lineages |
| Most common source | Respiratory tract (54.5%), then superficial sites (28.4%) and deep tissues or fluids (14.7%) |
| Antifungal susceptibility | High activity overall for azoles, echinocandins, and terbinafine |
Recovering a mold from a clinical sample does not by itself mean it caused disease, since airborne spores commonly contaminate respiratory and skin specimens. Clinicians interpret these results in context.
Is Cladosporium "Black Mold"?
Cladosporium colonies are often olive-green to black, so they are frequently called black mold. The fungus most people mean by that term, however, is Stachybotrys chartarum, which grows on persistently wet, cellulose-rich materials and is known for producing mycotoxins. Cladosporium's health concerns are primarily allergic rather than toxic. For more on the differences, see our article on whether black mold is dangerous.
Reducing Exposure
- Control moisture. Fix leaks, reduce condensation on windows, and keep indoor humidity moderate.
- Clean small areas promptly. Hard, non-porous surfaces can usually be cleaned. Porous materials with extensive growth often need replacement.
- Watch outdoor spore levels. Mold spore counts vary with season and weather, and thunderstorms can cause sudden spikes.[5]
- Get tested if you have asthma. Knowing whether you are sensitized to specific molds can guide avoidance and treatment. See our allergies and hay fever protocol for microbiome-related research on allergic disease.
When to See a Clinician
See a clinician if you have wheezing, shortness of breath, chest tightness, or allergy symptoms that worsen at home or in damp buildings, or if you have asthma that is becoming harder to control. People with weakened immune systems should seek care for new respiratory symptoms, fever, or sinus pain.
This page is for educational purposes and is not medical advice. Consult a qualified healthcare provider about mold exposure, allergies, or asthma.