Patent foramen ovale (PFO), a relatively common abnormality in adults, has been associated with migraine. Few studies also linked PFO with cluster headache (CH). To verify whether right-to-left shunt (RLS) is related to headaches other than migraine and CH, we used transcranial Doppler following microbubbles injection to detect shunts in 24 CH, 7 paroxysmal hemicrania (PH), one SUNCT, two hemicrania continua (HC) patients; and 34 matched controls. RLS was significantly more frequent in CH than in controls (54% vs. 25%, p=0.03), particularly above the age of 50. In the HC+PH+SUNCT group, RLS was found in 6 patients and in 2 controls (p=0.08). Smoking as well as the Epworth Sleepiness Scale correlated significantly with CH, smoking being more frequent in patients with RLS. PFO may be non-specifically related to trigeminal autonomic cephalalgias and HC. The headache phenotype in PFO patients probably depends on individual susceptibility to circulating trigger factors.