It could be the brand. Just like in generic anything, meds are no different. If you filled the brand name the first time, and filled generic the second, this could explain the difference in taste. Also (more of a longshot here) when your sinuses are congested things will taste differently. Are you less congested now that you were when you first had the syrup?
quinine
Codeine on its own tastes extremely bitter. If you have to take it in a solution it's best to mix it with something sweet like fruit squash or kool-aid.
The scientific name of bitter leaf is Vernonia amygdalina. It is a plant commonly used in traditional medicine for its bitter taste and medicinal properties.
bitter
Sweet is usually the opposite of bitter.Sweet, for example: bitter mustard and sweet chilli.
Alkaloids usually have a bitter taste
Adding sweetener such as sugar or honey will usually make bitter things sweet.
A balaustine is a roselike flower of the pomegranate, with a bitter taste and sometimes used as an astringent in folk medicine.
A bitter pill to swallow means something that is unpleasant, but true or important to hear. Medicine has a reputation for tasting bad, but you take it to get better. It is unpleasant but helpful. "It was a bitter pill to swallow when Jane was told that her son was a bully."
my answer is coffee, ampalaya, medicine, beer and unsweetened sweets and all green leafy vegetables.
Usually nothing, or something really really bitter.
Bitter Melon is the English name for Gobyab. Gobyab is from the gourd family. Its flesh is used in Asian cooking and a tea or broth for cooking can be made from dried bitter melon. The tea is very mild and does not have a strong bitter flavour. In traditional Chinese medicine, bitter melon can be used to aid digestion and lower blood sugar.