To compare the response to first-line medical treatment in treatment-naive acromegaly patients with pure growth hormone (GH)-secreting pituitary adenoma (GH-PA) and those with GH and prolactin co-secreting PA (GH&PRL-PA). Retrospective multicentric study of acromegaly patients followed from 2003 to 2023 in 33 tertiary Spanish hospitals with at least six months of first-line medical treatment. Baseline characteristics, first-line medical treatment strategies, and outcomes were analysed. We employed a multiple logistic regression full model to estimate the impact of some baseline characteristics on disease control after each treatment modality. Of the 144 patients included, 72.9% had a GH-PA, and 27.1% had a GH&PRL-PA. Patients with GH&PRL-PA were younger (43.9 ± 15.0 vs. 51.9 ± 12.7 years; p < 0.01) and harboring more frequently macroadenomas (89.7% vs. 72.1%, p = 0.03). First generation somatostatin receptor ligand (fgSRL) as monotherapy was given to 106 (73.6%) and a combination treatment with fgSRL and cabergoline in the remaining 38 (26.4%). Patients with GH&PRL-PA received more frequently a combination therapy (56.4% vs. 15.2%; p < 0.01). After 6 months of treatment, in the group of patients under fgSRL as monotherapy, those patients with GH&PRL-PA had worse control compared to GH-PAs (29.4% vs. 55.1%, p = 0.04). However, these differences in the rate of disease control between both groups disappeared when both received combination treatment with fgSRL and cabergoline. In GH&PRL-PA the biochemical control achieved with fgSRL as monotherapy is substantially worse than in patients harboring GH-PA, supporting the inclusion of cabergoline as first line medical treatment in combination with fgSRLs in these subgroups of patients.