Per Wikipedia-
Pseudoephedrine (commonly abbreviated as PSE) is a sympathomimetic amine commonly used as a decongestant. The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter preparations either as single-ingredient preparations, or more commonly in combination with antihistamines, paracetamol and/or ibuprofen. Consumers in North America, the United Kingdom, and Australia often refer to it as Sudafed, the trademark for a common brand of pseudoephedrine hydrochloride, although Pfizer now sells products without pseudoephedrine under the brand name (as Sudafed PE).
Unlike antihistamines, which modify the systemic histamine-mediated allergic response, pseudoephedrine only relieves nasal congestion commonly associated with colds or allergies. However, some users report rapid and effective relief from other allergic symptoms, including itchy and/or watery eyes, which may not have been provided effectively by antihistamines.
The advantage of oral pseudoephedrine over topical nasal preparations, such as oxymetazoline, is that it does not cause rebound congestion (rhinitis medicamentosa); however, it is more likely to cause adverse effects including hypertension.
Pseudoephedrine, also known as (-)-(1R,2R)-pseudoephedrine or (-)-pseudoephedrine, is the optical isomer of D-pseudoephedrine. It has fewer side-effects, fewer central nervous system (CNS) stimulatory effects, does not reduce to D-methamphetamine (which is the enatiomer used as a recreational drug), and yet it retains its efficacy as a decongestant.
Ephedrine (EPH) is a sympathomimetic amine similar in structure to the synthetic derivatives amphetamine and methamphetamine. Ephedrine is commonly used as a stimulant, appetite suppressant, concentration aid, decongestant and to treat hypotension associated with regional anaesthesia. Chemically, it is an alkaloid derived from various plants in the genus Ephedra (family Ephedraceae). It is most usually marketed in the hydrochloride and sulfate forms.
In traditional Chinese medicines, the herb ma huang (Ephedra sinica) contains ephedrine and pseudoephedrine as its principal active constituents. The same is true of other herbal products containing extracts from Ephedra species. Nagayoshi Nagai was the first one to isolate ephedrine from Ephedra vulgaris in 1885. The substance called soma mentioned in old Hindu books such as the Rig Veda, may have been ephedra extract.
The production of ephedrine in China has become a multi-million dollar export industry. Companies producing for export extract US$13 million worth of ephedrine from 30,000 tons of ephedra annually, 10 times the amount that is used in traditional Chinese medicine.[1]