| Olmesartan medoxomil 10mg, 20mg & 40mg Film-coated tablets | - |  29/08/19 |  03/01/20 | olmesartan medoxomil | Gerard Laboratories |
| Olumiant 2 mg and 4 mg Film-Coated Tablets | | 26/11/19 | 26/11/19 | Baricitinib | Eli Lilly and Company (Ireland) Limited |
| Omacor 1000 mg Soft Capsules | - | 06/12/19 | 16/01/20 | 90% Omega-3 acid ethyl esters | Mylan IRE Healthcare Limited |
| Omeprazole Mylan 10mg, 20mg, 40mg gastro-resistant capsules, hard | - | 08/06/17 | 13/06/17 | Omeprazole | Gerard Laboratories |
| Omesar 10mg, 20mg and 40mg Film-Coated Tablets | - | 22/06/17 | 21/03/19 | olmesartan medoxomil | A. Menarini Pharmaceuticals Ireland Ltd |
| Omesar Plus 20 mg/12.5 mg & 20 mg/25 mg Film-coated tablets | - | 27/03/19 | 27/03/19 | Hydrochlorothiazide, olmesartan medoxomil | A. Menarini Pharmaceuticals Ireland Ltd |
| Omesar Plus 40 mg/12.5 mg & 40 mg/25 mg film-coated tablets | - | 27/03/19 | 27/03/19 | Hydrochlorothiazide, olmesartan medoxomil | A. Menarini Pharmaceuticals Ireland Ltd |
| Omnexel | - | 27/01/20 | 22/01/20 | Tamsulosin Hydrochloride | Astellas Pharma Co. Ltd |
| Onbrez Breezhaler 150 microgram inhalation powder, hard capsules | - | 07/02/20 | 18/12/19 | Indacaterol maleate | Novartis Ireland Limited |
| Onbrez Breezhaler 300 microgram inhalation powder, hard capsules | - | 07/02/20 | 18/12/19 | Indacaterol maleate | Novartis Ireland Limited |
| Oncaspar (solution) | | 20/05/19 | 20/05/19 | pegaspargase | Servier Laboratories Ireland Ltd |
| Oncaspar 750 U/ml powder for solution for injection/infusion | | 03/10/19 | 17/02/20 | pegaspargase | Servier Laboratories Ireland Ltd |
| Ondansetron 2mg/ml Solution for Injection or Infusion | - | 18/03/20 | 18/03/20 | Ondansetron hydrochloride dihydrate | Gerard Laboratories |
| One-Alpha 0.25 mcg Capsules | - | 28/10/16 | 24/11/17 | Alfacalcidol | LEO Pharma |
| One-Alpha 1 mcg Capsules | - | 28/10/16 | 16/02/17 | Alfacalcidol | LEO Pharma |
| One-Alpha Drops | - | 17/05/19 | 26/04/19 | Alfacalcidol | LEO Pharma |
| Onglyza 2.5 mg Film-Coated Tablets | - | 19/03/20 | 19/03/20 | Saxagliptin hydrochloride | AstraZeneca Pharmaceuticals (Ireland) DAC |
| Onglyza 5 mg Film-Coated Tablets | - | 19/03/20 | 19/03/20 | Saxagliptin hydrochloride | AstraZeneca Pharmaceuticals (Ireland) DAC |
| Opatanol 1mg/ml eye drops solution | - | 11/12/19 | 08/04/19 | Olopatadine (as hydrochloride) | Novartis Ireland Limited |
| OPDIVO 10 mg/mL concentrate for solution for infusion | | 23/01/20 | 23/01/20 | Nivolumab | Bristol-Myers Squibb Pharma EEIG |
| Opsumit 10mg | - | 04/03/20 | 04/03/20 | Macitentan | Actelion, a division of Janssen-Cilag International NV |
| Opticrom 2% w/v Eye Drops Solution | - | 12/12/16 | 07/08/17 | Sodium Cromoglicate | SANOFI |
| Opticrom Allergy 2%w/v Eye Drops, Solution | - | 14/03/18 | 11/12/18 | Sodium Cromoglicate | SANOFI |
| Opticrom Allergy Single Dose 2%w/v Eye Drops, solution | - | 11/05/17 | 27/11/19 | Sodium Cromoglicate | SANOFI |
| Optrex Clear Eyes Eye Drops | - | 15/01/20 | 19/01/18 | Hamamelis, Naphazoline Hydrochloride | Reckitt Benckiser Ireland Limited |
