If you turn right outside the IBIS and walk down to the next turning, Avenida Basilio Teles, (Post Office - CTT is on the corner.) Turn Right and continue down to the next street:
Avenida Columbano Bordalo Pinheiro
Cross over and turn right along ths pavement. Half way along you will find (according to listings):
Farmácia Aguiar
Avenida Columbano Bordalo Pinheiro, 98-A/B
1070-066 LISBOA
TEL: 217260934
EMAIL: farmacia.aguiar@clix.pt
There are several good cold medicines on sale in Portugal. However, I would go to the pharmacy and talk to them. I am sure that at least one of the pharmacists will speak english as this area is full of hotels and Intĺ companies.