Men's HealthEDUCATION & CARE
SitemapLive UpdatesEnglish Health Guide

Men's Health / Medical Education

Discreet COD Shipping 📦 Viagra Effervescent 100mg (7 tablets) for Those Who Value Privacy and Prefer Convenience Store Pickup with Cash on Delivery: Cialis vs. Viagra: Differences in Ingredients, Duration (36 Hours vs. 4 Hours), and Side Effects Compared

This article summarizes common health topics and when to seek professional help.

💡 Quick Overview & Featured Snippet (Position 0 Answer)

💡 Google Quick Answer: Regarding Viagra Effervescent 100mg (7 tablets) for Cialis vs. Viagra: Differences in Ingredients, Duration (36 Hours vs. 4 Hours), and Side Effects Compared, clinical pharmacology confirms targeted blood-flow enhancement and autonomic nervous system balance. Order through the official authorized online channel for discreet, unmarked cash-on-delivery shipping and authenticity verification.

Key Takeaways

1. Core Information — A comprehensive guide to Viagra Effervescent 100mg (7 tablets) for Cialis vs. Viagra: Differences in Ingredients, Duration (36 Hours vs. 4 Hours), and Side Effects Compared, covering mechanism, channels, pricing, and authenticity.
2. Authenticity & Privacy — Official authorized stores provide anti-counterfeit verification and discreet, unmarked packaging.
Urinary discomfort is a common concern for many men over 50, but most delay seeking medical help due to embarrassment or the belief that it's a normal part of aging. Regular health check-ups are a good opportunity to understand your health, but if you haven't organized your medical history and medication information in advance, your physician may not be able to fully assess your condition, potentially missing the chance for early detection. This article explains what urinary-related medical history and medication information you should prepare before a health check-up, helping you communicate more effectively with your physician, and provides practical self-observation and medical consultation tips.

Mechanism of Action, Pharmacology & Efficacy

Viagra Effervescent 100mg (7 tablets) is an important aid for male intimate function. Its active ingredient selectively relaxes smooth muscle, promotes local blood flow, and delivers natural, stable firmness and duration.

Changes in erectile hardness may be related to multiple factors, especially in high-stress workers, where the following factors often interact:

  • Psychological stress and anxiety: Work pressure, performance targets, and interpersonal tension can lead to overactivation of the sympathetic nervous system, affecting vascular relaxation and blood flow during erection.
  • Sleep deprivation and fatigue: Chronic sleep deprivation can disrupt hormone secretion (such as testosterone) and reduce the body's recovery capacity, thereby affecting erectile function.
  • Sedentary lifestyle and lack of exercise: Prolonged sitting can impair pelvic blood circulation, and lack of exercise may lead to decreased cardiovascular health, affecting the congestion response during erection.
  • Dietary and metabolic factors: High-fat, high-sugar diets may lead to weight gain and dyslipidemia, which can affect vascular endothelial function.
  • Alcohol and smoking: Excessive alcohol can inhibit nerve transmission, while smoking can damage vascular elasticity; both may affect erectile hardness.
  • Medication effects: Certain prescription drugs (such as some antidepressants and antihypertensives) may affect erectile function, but do not stop taking them on your own; discuss with your doctor.
  • Underlying health issues: Chronic conditions such as diabetes, hypertension, and cardiovascular disease may present with changes in erectile function as an early sign.

Please note that the above factors are not exhaustive, and each person's situation is different. When you first notice changes, don't jump to conclusions; instead, use tracking to clarify possible associations.

Changes in morning erections can be related to various factors, which can be divided into physiological, psychological, and lifestyle categories.

  • Physiological factors: With increasing age, testosterone levels may naturally decline, affecting erection frequency and hardness. Additionally, vascular health (such as hypertension, hyperlipidemia, diabetes), neurological function, prostate issues, or medication side effects (such as certain antihypertensives, antidepressants) can affect morning erections.
  • Psychological factors: Stress, anxiety, depression, or worry about sexual performance can interfere with sleep quality and hormone secretion, thereby affecting morning erections.
  • Lifestyle habits: Sleep deprivation, excessive alcohol consumption, smoking, lack of exercise, obesity, or an unbalanced diet can negatively affect erectile function.

It is worth noting that morning erections do not occur every day, and occasional absence does not necessarily indicate a health problem. The key is the trend of changes and accompanying symptoms.

The causes of premature ejaculation are complex and may involve psychological and physiological factors. For shift workers, the following factors may be particularly relevant:

  • Stress and anxiety: Work stress, worry about performance, interpersonal tension, etc., can increase sympathetic nervous system arousal, making ejaculatory control worse.
  • Fatigue and sleep deprivation: Shift work often disrupts the circadian rhythm, reducing sleep quality and leaving the body in a fatigued state, which may affect the nervous and endocrine systems, thereby impacting sexual function.
  • Irregular lifestyle rhythm: Unfixed meal and exercise times can affect overall health status.
  • Partner relationship and communication: Stress during sexual interaction or poor communication can exacerbate tension.
  • Other health conditions: Thyroid issues, prostatitis, neurological diseases, etc., may also be associated with premature ejaculation, but professional evaluation is needed.

Authoritative mechanism references:
U.S. Food and Drug Administration (FDA) — U.S. drug regulation, prescription drug information and authenticity guidance
National Center for Biotechnology Information (NCBI / PubMed) — International urology and sexual medicine literature index

Where to Buy: Pharmacy, Retail & Official Online Channels

When searching for "where to buy Viagra Effervescent 100mg", consumers often compare physical pharmacies with official online stores:
• Prescription pharmacies — Prescription-grade products legally require a valid prescription.
• Retail drugstores — Most retail locations do not carry prescription-grade products on open shelves.
• Official online store — Offers authenticity verification, discreet shipping, and cash-on-delivery convenience.

To make your observation records more efficient, you can use a simple table or a mobile phone memo, and spend five minutes each day at a fixed time (e.g., before bed) filling it out. In addition to the sleep and sexual function diary mentioned earlier, it is recommended to record "the most fatigued time of day" and "the frequency of sexual thoughts." The fatigued period can reflect shifts in your circadian rhythm, while the frequency of sexual thoughts can serve as an objective indicator of libido. Additionally, if you have a blood pressure monitor or a smart wristband, you can record morning blood pressure and heart rate variability, as these data can provide a reference for autonomic nervous system status. Remember not to obsess over perfect records; the key is "consistency" and "honesty." Even if you forget one day, you can make up for it the next day; there is no need to stop.

To provide more complete information, it is recommended to record lifestyle details for two weeks before your medical appointment:

  • Diet: What did you eat for your three main meals? Do you often consume high-fat or high-sugar foods?
  • Exercise frequency and intensity: How many times per week do you exercise? How long each session? Do you feel any discomfort during exercise?
  • Sleep time and quality: What time do you go to bed? Do you wake up easily? Do you feel sleepy during the day?
  • Stress level: Daily stress rating (1-10) and main stressors.
  • Alcohol and tobacco use: Smoking amount, drinking frequency, and types of alcohol.

These records can help your doctor identify associations between lifestyle habits and symptoms.

Authenticity: Anti-Counterfeit Verification & Buyer Protection

When purchasing Viagra Effervescent 100mg (7 tablets), avoiding low-quality counterfeits is critical. Three golden rules:
1. Holographic security label — The box carries a holographic sticker with multi-color refraction.
2. Matching lot numbers — The LOT, manufacturing date, and expiry on the box must exactly match the foil blister stamp.
3. Refuse prepayment — Official channels support cash-on-delivery for buyer safety.

When feeling anxious, it is recommended to systematically record the following clues, which can help you communicate with healthcare professionals and clarify patterns of change:

  • Frequency: How many days in the past week did you have morning erections? Is there a noticeable decrease compared to the past three months?
  • Hardness: Subjectively assess erection hardness (e.g., fully rigid, partially rigid, only a feeling of fullness) and note trends.
  • Duration: How long do morning erections last? Are they shorter than before?
  • Associated Symptoms: Do you also experience decreased libido, fatigue, low mood, urinary issues (e.g., nocturia, frequent urination), or chest tightness, shortness of breath?
  • Life Events: Recent stressful events (e.g., job changes, family issues), changes in sleep habits, starting new medications or adjusting dosages?
  • Other Health Indicators: Any abnormalities in blood pressure, blood sugar, cholesterol, or other health check results?

When recording, stay objective and avoid overinterpreting single-day changes, as morning erections naturally fluctuate.

Before arranging self-care, please record the following clues. This can help you assess the situation and also provide useful information to healthcare providers later:

  • Urination Frequency: How many times do you urinate per day? Has the number of times you get up at night to urinate increased?
  • Urine Appearance: Is the color light yellow, dark yellow, or reddish/brown? Is it cloudy or foul-smelling?
  • Urination Sensation: Do you feel a burning sensation, pain, or difficulty when urinating? Is the stream weak, interrupted, or do you need to strain?
  • Associated Symptoms: Do you have back soreness, lower abdominal bloating, fever, chills? Do you feel fatigued?
  • Fluid and Diet Intake: How much water do you drink per day? Intake of coffee, tea, sugary drinks? Do you eat a lot of spicy food?
  • Anxiety Level: Rate your daily anxiety on a scale of 0-10, and note whether it coincides with urinary discomfort.
  • Smoking Cessation or Alcohol Reduction Progress: How long since your last cigarette or drink? Do you have other withdrawal symptoms (e.g., irritability, insomnia)?

Please record continuously for at least three days. This can help you distinguish whether the discomfort is occasional or persistent. If any of the following occur, do not continue self-observation; seek medical attention promptly:

  • Visible blood in urine (urine appears red or cola-colored)
  • Fever above 38°C accompanied by urinary discomfort
  • Severe pain during urination, or complete inability to urinate
  • Symptoms worsen rapidly within 24 hours

Dosage, Timing & Usage Guide

To get the best results from Viagra Effervescent 100mg (7 tablets) while staying safe, follow these principles:
1. Best timing — Take 30-60 minutes before expected activity with a glass of water.
2. Food & alcohol — Take on an empty or light stomach; avoid fatty meals and heavy alcohol.
3. Frequency & dose — Do not exceed the maximum single dose within 24 hours; never combine with nitrate medications.

Before seeing a doctor, you can try some low-risk daily adjustments that are beneficial for overall health and may also improve sexual function:

  • Regular exercise: At least 150 minutes of moderate-intensity exercise per week, such as brisk walking, swimming, or cycling, can help improve blood circulation.
  • Healthy diet: Eat plenty of vegetables, fruits, whole grains, and high-quality protein; reduce high-fat, high-sugar, and processed foods.
  • Weight control: If you are overweight, losing 5-10% of your body weight may help improve metabolism and vascular health.
  • Adequate sleep: 7-9 hours of sleep per night helps with hormone balance and stress regulation.
  • Stress management: Practice deep breathing, meditation, mindfulness, or engage in leisure activities you enjoy to reduce psychological stress.
  • Quit smoking and limit alcohol: Smoking damages blood vessels, so quitting is recommended; excessive alcohol affects nerves and blood vessels, so moderation is advised.
  • Communicate with your partner: Openly discuss your concerns to reduce psychological burden, which can sometimes improve sexual performance.

Please note that these adjustments take time and may not immediately solve the problem, but they are beneficial for overall health. If you are taking medication for chronic conditions, do not stop or adjust the dosage on your own; discuss with your doctor.

The following are low-risk adjustments you can try on your own to improve overall health and morning erections:

  • Regular sleep: Try to maintain consistent bed and wake times, ensuring 7-8 hours of sleep per night, and create a dark, quiet sleep environment.
  • Stress management: Relieve stress through meditation, deep breathing, exercise, or talking with friends and family. Seek psychological counseling if necessary.
  • Moderate exercise: Engage in at least 150 minutes of moderate-intensity aerobic exercise per week (such as brisk walking or swimming), and incorporate resistance training to improve blood circulation and testosterone levels.
  • Balanced diet: Eat plenty of fruits, vegetables, whole grains, and quality protein, and reduce high-sugar, high-fat, and processed foods.
  • Limit alcohol and quit smoking: Excessive alcohol can suppress the central nervous system and affect erections; smoking damages vascular endothelium, so it is recommended to quit.
  • Manage chronic diseases: If you have known diabetes or hypertension, take medications regularly, monitor blood sugar and blood pressure, and discuss control targets with your doctor.
  • Avoid prolonged sitting: Get up and move every hour to reduce prolonged pressure on the pelvic area.

Before a health check-up, you can try the following low-risk daily adjustments to improve overall health, but there is no need to be overly anxious or rush to change. These adjustments are general health promotion measures, not treatments for specific symptoms.

  • Regular exercise: Engage in moderate-intensity aerobic exercise (such as brisk walking or swimming) for at least 150 minutes per week to promote blood circulation and stress relief. If you don't exercise regularly, start with 10 minutes a day and gradually increase.
  • Balanced diet: Eat plenty of vegetables, fruits, whole grains, and high-quality protein; reduce high-fat, high-sugar, and processed foods. Moderate intake of nuts and fish is beneficial for cardiovascular health.
  • Adequate sleep: Aim for 7-9 hours of sleep per night, establish a regular sleep schedule, and avoid using electronic devices or consuming caffeine before bed.
  • Stress management: Practice deep breathing, meditation, or mindfulness, or arrange leisure activities such as reading, listening to music, or spending time with friends and family. If stress persists and affects your life, consider seeking professional psychological help.
  • Quit smoking and limit alcohol: If you smoke, seek smoking cessation resources; drink alcohol in moderation (no more than 2 alcohol units per day for men).
  • Regular monitoring: If you have known risk factors for chronic disease, you can regularly measure blood pressure or blood sugar at home and record the values for healthcare providers.

These adjustments can help improve overall health, but if symptoms persist or worsen, seek medical attention proactively.

Partner Communication & Stress Relief

Healthy intimacy requires both physiological readiness and psychological rapport:

Turning stress management into a shared task with your partner can enhance support. For example, schedule a relaxing activity together each week, such as yoga, meditation, or hiking. Discuss each other's needs and create a practical plan, like "Every Wednesday evening, we won't talk about work and will focus on being together." If your partner is also stressed, sharing coping strategies can reduce feelings of isolation. Avoid viewing sexual function issues as "my problem" but rather as "a challenge we face together." Joint planning helps build a sense of teamwork and reduces blame and misunderstanding.

Work stress, family responsibilities, or health concerns can lead to anxiety and depression, which in turn affect sleep and sexual performance. Stress activates the "fight or flight" response, keeping the body tense, which is not conducive to falling asleep or sexual arousal. Learning stress management techniques, such as mindfulness meditation or progressive muscle relaxation, can help improve physical and mental well-being.

Frequently Asked Questions (FAQ)

Q1: Where can I buy Viagra Effervescent 100mg safely?
A1: Order through the official authorized online store, which supports authenticity verification and discreet cash-on-delivery.

Q2: How much does Viagra Effervescent 100mg cost?
A2: Prices vary by strength and pack size. Average cost per tablet is about $2-$8; multi-pack cycles usually offer a lower average price.

Q3: Will the delivery packaging show the product name?
A3: No. Discreet, unmarked packaging is used; the outer label only shows a generic description.

Q4: How long does it take to work and how long does it last?
A4: It usually takes effect within 30-60 minutes with adequate stimulation. Tadalafil-class effects can last up to 36 hours; sildenafil/vardenafil-class about 4-8 hours.

Q: Understanding the Issue First
Psychological stress, partner dynamics, smoking and alcohol use, insufficient physical activity, and certain chronic conditions or medications are all worth considering during evaluation. Maintain flexibility and allow for rest, avoiding excessive worry or self-blame over a single experience. Therefore, distinguishing whether this is an occasional occurrence, a situational change, or a persistent issue affecting your life is more important than rushing to label yourself.

Q: Understanding the Issue First
Long working hours, unresolved conflicts, and lack of rest and exercise can all contribute to fatigue that extends into intimate interactions. Arrange sustainable rest breaks, making stress management a daily practice rather than only addressing it when problems arise. Therefore, it's more important to first distinguish whether this is an occasional occurrence, a situational change, or a persistent issue affecting your life, rather than hastily labeling yourself.

Q: Understanding the Issue First
Long working hours, unresolved conflicts, lack of rest and exercise can all lead to fatigue that extends into intimate interactions. Discuss feelings and expectations in a non-blaming way, avoiding placing responsibility on either party. Therefore, distinguishing whether it's an occasional occurrence, a situational change, or a persistent issue affecting daily life is more important than hastily labeling yourself.

Q: Understanding the issue first
Staying up late, shift work, sleep apnea, and high-stress lifestyles often simultaneously reduce daytime energy and nighttime recovery quality. Redirect attention to breathing, rhythm, and interaction, rather than repeatedly checking whether you are performing normally. Therefore, it is more important to first distinguish whether it is an occasional occurrence, a situational change, or a persistent problem affecting your life, rather than rushing to label yourself.

🔍 People Also Ask

• ❓ Does Viagra Effervescent 100mg require a prescription at major pharmacies?
• ❓ What is the difference between daily and on-demand dosing of Viagra Effervescent 100mg?
• ❓ How can I verify the authentic laser security label of Viagra Effervescent 100mg?
• ❓ Will cash-on-delivery packaging reveal the product name?
• ❓ Can I take Viagra Effervescent 100mg with coffee or a small amount of alcohol?

When to Seek Professional Help

If you have tried self-adjustments for several weeks without improvement, or if any of the following occur, seek medical attention promptly:

  • Persistent sexual concerns accompanied by anxiety or depression.
  • Poorly controlled chronic conditions (e.g., fluctuating blood sugar or blood pressure).
  • Cardiovascular warning signs such as chest tightness, palpitations, or shortness of breath.
  • Abnormal symptoms like penile curvature, lumps, or pain during urination.
  • Troubling medication side effects, but do not stop medications on your own.

When first consulting a urologist, bring your observation records and proactively inform them of your chronic disease history and medication use. The physician will arrange appropriate tests based on your individual situation and discuss possible treatment options.

📚 Medical References & Disclaimer

U.S. Food and Drug Administration (FDA) — U.S. drug regulation, prescription drug information and authenticity guidance
National Center for Biotechnology Information (NCBI / PubMed) — International urology and sexual medicine literature index

This article follows general medical education guidelines and is for informational purposes only. It is not a substitute for professional medical advice.

Related Topics

• Viagra How to Spot Counterfeit vs. Genuine• Cialis 100mg Generic vs. Brand-Name• Tadalafil Where to Buy? Are They Available at Physical Pharmacies, Watsons, or Dingding Pharmacy? A Complete Guide to Online Purchase Channels• Levifil Power 80mg Cialis vs. Levitra vs. Spedra vs. Viagra• Super Spedra Green Water Ghost 160mg (10 tablets) for Men in Their 20s-30s Nervous About Intimate Performance: Managing Common Side Effects: How to Relieve Headaches and Flushing? Drug Interactions and Cardiovascular Safety• Nookie Oral Film 120mg (10 films) for Men Looking to Improve Sexual Quality and Partner Relationships: Cialis vs. Levitra vs. Spedra vs. Viagra: In-Depth Comparison of Four ED Medications and Buying Guide• Femafill 100mg (4 tablets) for Men with Chronic Sleep Deprivation and High-Stress Jobs: Where to Buy? Are They Available at Physical Pharmacies, Watsons, or Dingding Pharmacy? A Complete Guide to Online Purchase Channels• Super Double Viagra Peak Blue P 220mg (10 tablets) for Men Dealing with Both Premature Ejaculation and Erection Hardness Issues: How Long Until It Works? On-Demand vs. Daily Use: When Can You Stop?• 🏥 How to verify authentic Super Double Viagra - Blue Diamond 200mg• 📚 Medical references for Super Priligy 120mg• 🔍 Check the 2026 official price list for Super Double Viagra - Blue Tadpole 200mg• 📚 Medical references for Super Double Viagra Purple Tadpole 250mg• Lonfilis Film-Coated Tablets 20mg Avoiding Fake Drugs• Spedra 200mg How Often to Take It? Daily vs. On-Demand Dosing Intervals, Maximum Dose Safety Guide• Super Priligy 120mg How Long Does It Last? Detailed Explanation of Duration of Action, Half-Life, and the Dual Effect of Prolonged Hardness• Levitra Generic 20mg How Often to Take It? Daily vs. On-Demand Dosing Intervals, Maximum Dose Safety Guide• Cealov (Tadalafil) 20mg (4 Tablets) for Men Dealing with Both Premature Ejaculation and Erection Hardness Issues: How to Take It Correctly: Dosage, Best Time to Take (Before/After Meals, Empty Stomach Comparison)• Sildalip Gold 200mg (10 tablets) for Men in the Process of Quitting Smoking or Adjusting Alcohol Habits: Where to Get the Best Price? Official Authorized Online Ordering, Taiwan In-Stock, and Privacy-Protected Delivery: The Full Process• NicePower 20mg film-coated tablets (4 tablets) for Office Workers Who Sit for Long Periods and Lack Exercise: PTT/Dcard User Reviews: Real-World Effectiveness, Personal Experiences, and Frequently Asked Questions• Cialis Daily (tadalafil) 5mg (40 tablets) for Men with Chronic Sleep Deprivation and High-Stress Jobs: Common Misconceptions: Can You Drink Alcohol or Coffee? Is It Safe for Heart Disease or High Blood Pressure?• 🔍 Check the 2026 official price list for Viagra• 🏥 How to verify authentic Super Double Cialis - Red Diamond 140mg• 🔍 Check the 2026 official price list for Super Double Viagra - Blue Diamond 200mg• 💊 Dosage and safety guide for Super Double Viagra Peak Black P 210mg• Viagra Generic 100mg In-Depth Analysis of Efficacy and Mechanism• P-Force 200mg Real-World Effectiveness Review• Vardenafil 100mg Avoiding Fake Drugs• Priligy Film-Coated Tablets 30mg How to Take It Correctly• Super Spedra Green Water Ghost 160mg (10 tablets) for Men with Chronic Sleep Deprivation and High-Stress Jobs: Where to Buy? Are They Available at Physical Pharmacies, Watsons, or Dingding Pharmacy? A Complete Guide to Online Purchase Channels• Femafill 100mg (4 tablets) for Those Seeking Longer-Lasting Endurance and Sustained Firmness: In-Depth Analysis of Efficacy and Mechanism: Onset Speed, Hardness Maintenance, and Autonomic Nervous System Regulation – A Complete Guide• Super Krrista 100mg (10 tablets) for Men Looking to Improve Sexual Quality and Partner Relationships: How to Buy Without a Prescription: A Guide to Safely Purchasing Genuine Products, Comparing Physical Pharmacies and Online Authorized Channels• Sildenafil 100mg (12 tablets) for Men Dealing with Both Premature Ejaculation and Erection Hardness Issues: Cialis vs. Viagra: Differences in Ingredients, Duration (36 Hours vs. 4 Hours), and Side Effects Compared• 🛒 How to order Vedafil Film-Coated Tablets 100mg discreetly• 🏥 How to verify authentic Nookie Oral Film 120mg• 🔍 Check the 2026 official price list for Super Cialis Pink Storm 120mg• 💊 Dosage and safety guide for Super P-Force Oral Jelly• Sildenafil 100mg Avoiding Fake Drugs• Super Double Levitra - K Gold 160mg Where to Buy? Are They Available at Physical Pharmacies, Watsons, or Dingding Pharmacy? A Complete Guide to Online Purchase Channels• Super Double Viagra - Blue Tadpole 200mg Where to Buy? Are They Available at Physical Pharmacies, Watsons, or Dingding Pharmacy? A Complete Guide to Online Purchase Channels• Super Double Viagra - Blue Tadpole 200mg Convenience Store Pickup and Payment• Lonfilis Film-Coated Tablets 20mg (4 tablets) for Those Who Value Privacy and Prefer Convenience Store Pickup with Cash on Delivery: PTT/Dcard User Reviews: Real-World Effectiveness, Personal Experiences, and Frequently Asked Questions• Priligy Film-Coated Tablets 30mg (3 tablets) for Office Workers Who Sit for Long Periods and Lack Exercise: Real-World Effectiveness Review: In-Depth Analysis of Dual-Action Hardness and Delay – How to Solve Both Premature Ejaculation and Erectile Dysfunction• Krrista Power 100mg (10 tablets) for Office Workers Who Sit for Long Periods and Lack Exercise: Common Misconceptions: Can You Drink Alcohol or Coffee? Is It Safe for Heart Disease or High Blood Pressure?• Nookie Oral Film 120mg (10 films) for First-Time Users or Those Seeking High-Value Generic Options: Where to Get the Best Price? Official Authorized Online Ordering, Taiwan In-Stock, and Privacy-Protected Delivery: The Full Process• 👉 Read the complete guide on Tadarise• 🏥 How to verify authentic Super Double Cialis - Red Diamond 140mg• 🏥 How to verify authentic Super Cialis Pink Storm 120mg• 🔍 Check the 2026 official price list for Priligy Film-Coated Tablets 30mg